OMG OMG-OCUP2-FOUND100 OMG Certified UML Professional 2 (OCUP 2) - Foundation Level Exam Practice Test

The provided image depicts a block diagram of a sensor controller represented as a state machine. The state machine transitions between the following states:

• Initializing
• Calibrating
• Ready
• Acquiring Data

The question specifies the state machine starts in the Ready state and theacquireDataevent triggers the transition.

Analyzing the image, we can identify the following behaviors for the scenario:

• logStatus: This behavior is depicted in the diagram as the first action upon exiting the Ready state. It most likely logs the current state of the sensor controller.
• deploy: The transition from Ready to Acquiring Data triggers the deploy behavior. This likely involves preparing the sensor for data acquisition.
• scanTarget: Upon entering the Acquiring Data state, the scanTarget behavior is initiated. This suggests the sensor controller is actively collecting data from the target.

Therefore, the complete sequence of behaviors islogStatus, followed bydeploy, and lastlyscanTarget, before reaching the Acquiring Data state.

Justification for excluding other options:

• Option A (deploy only) excludes the initial state logging and target scanning actions.
• Option B (logStatus.deploy) excludes the target scanning upon entering the Acquiring Data state.
• Option C (deploy, scanTarget) omits the initial state logging.
• Option E (logStatus.deploy.scanTarget.logStatus) includes an extra logStatus action after target scanning, which is not supported by the diagram.

In conclusion, based on the state machine diagram and the behavior descriptions, option D (logStatus.deploy.scanTarget) accurately reflects the sequence of actions that occur before the sensor controller arrives at the Acquiring Data state.

In the given UML package diagram fragment, various elements are listed with stereotypes indicating their nature («class», «interface»). Stereotypes are used in UML to extend the vocabulary of UML in order to create new kinds of building blocks. They are typically enclosed in guillemets (« »).

The last element, 'six', does not have a stereotype indicating whether it's a class, interface, or some other kind of element. This lack of a stereotype leads to ambiguity about the nature of 'six'. Therefore, the fragment is considered invalid due to this omission.

All the other options do not constitute an error in the UML fragment: A) A list of elements is allowed in a package body. B) Visibility is not required for every element, especially within package diagrams. C) Interfaces are allowed in packages. D) Private elements are allowed in a package. E) Protected elements are also allowed in a package.

Therefore, the correct answer is:

F. Element six is missing its stereotype.

In the second diagram provided, we see four messages: 'x', 'y', 'z', and 'p'. The vertical positioning of these messages indicates their order in time.

Option A states that "Sending message x is the first occurrence that happens." This could be true but is not necessarily always true, as there could be other messages or interactions before 'x' that are not shown in this part of the diagram.

Option B states that "Sending message z will happen after receiving message x." This is always true because the lifeline for 'v2[C]' shows the reception of 'x' before sending 'z'. In sequence diagrams, the vertical position indicates the sequence of events, and 'z' is clearly below 'x' on the 'v2[C]' lifeline.

Option C, "Sending message y will happen before sending message z," is not necessarily true because the messages 'y' and 'z' are sent by different lifelines, and there is no explicit ordering between them.

Option D, "Sending message p will happen before receiving message y," is not necessarily true as 'p' and 'y' involve different lifelines, and no ordering is specified between these interactions.

Therefore, the correct answer is:

B. Sending message z will happen after receiving message x.

The diagram shows a package Pckg that includes two classes G and H with a one-to-many association between them. The multiplicity '1..5' near class G on the 'gh' association end suggests that for each H object, there should be between 1 to 5 associated G objects. However, the '*' (multiplicity many) near class H on the 'gh' association end indicates that a G object can be associated with zero or more H objects. This implies that it's possible to have a G object that is not associated with any H object.

References:

• UML 2.x Superstructure Specification: Multiplicity notations and association rules are clearly defined in the UML specifications, which detail the semantics of multiplicities and their implications for object association.
• UML 2.x Infrastructure Specification: Further explains the basic constructs of the UML metamodel, which underpin the interpretation of multiplicities in associations.

In UML, an Object Diagram is a type of static structure diagram that shows a snapshot of the detailed state of a system at a point in time. It focuses on some particular set of objects and attributes, and the links between them. When it comes to the number of instances that can be represented in an Object Diagram, it can range from zero (in cases where the diagram is used to show that no instances of a class exist under certain conditions) to many instances. Therefore, an Object Diagram can show 0 instances, 1 instance, or many instances, which is represented by the multiplicity notation 0..*.

Therefore, the correct answer is:

D. 0..*

The diagram shows a UML Sequence Diagram where two messages are being exchanged between lifelines representing instances of objects:m(C)is being sent fromv1tov2, andm(D)is being sent back fromv2tov1.

In a sequence diagram, the vertical order of message arrows shows the sequence of interactions, with time proceeding down the page. Since the messagem(C)is shown abovem(D), this means thatm(C)occurs beforem(D). The receipt ofm(C)byv2[B]must therefore occur beforev2[B]can sendm(D)back tov1[B].

Therefore, the statement "Receivingm(C)must come before sendingm(D)" is always true in this diagram.

B, C, and D are not necessarily true based on the diagram alone: B) "Sending m(D) is the first occurrence of this scenario" is not depicted. C) "Receiving m(D) is the last occurrence of this scenario" is also not depicted. D) "All occurrences of v[1] will happen before all occurrences of v[3]" is not something we can infer from this diagram since v[3] is not involved in the interactions shown.

Therefore, the correct answer is:

A. Receiving m(C) must come before sending m(D).

In UML, a filled diamond represents a composite aggregation, also known as a composition. It indicates a whole-part relationship with strong ownership and coincident lifetime of the parts with the whole. Here's what it means in relation to the options provided:

A. This is partially correct. A filled diamond indeed indicates that the Ship instance is responsible for the existence of the associated Person instances, but it is not complete as it does not explicitly state that the Person instances will be deleted when the Ship instance is deleted.

B. This option is the most accurate. A filled diamond represents a composite aggregation, which means that the existence of the Person instances (parts) isdependent on the Ship instance (whole). When the Ship instance is deleted, so are the Person instances it contains.

C. The filled diamond is not a placebo; it has a well-defined meaning in UML, indicating strong ownership and lifecycle dependency between the whole and the part.

D. While the filled diamond does indicate ownership, it specifies more than just an attribute relationship; it indicates that the Ship class has a composition relationship with the Person class. This means that the Ship object contains Person objects as parts of itself, not just as an attribute reference.

E. The filled diamond is connected to the Ship class, not the Person class, so this statement is incorrect. The composition relationship is from Ship to Person, not the other way around.

Based on the UML specification for composite aggregation, the most accurate statement isB: Class Person's existence depends on the ship. It will get deleted when the ship gets deleted. This aligns with the definition of composite aggregation, where the part's lifecycle is dependent on the whole's lifecycle.

In the development of a domain model, the prime responsibility for decision-making should ideally rest with the users, as they are the ones who will be using the system operationally. Users have the most direct and frequent interactions with the system, making them best positioned to provide relevant insights into what the system should do and how it should behave to meet their needs effectively. While other stakeholders such as customers, project managers, and developers play significant roles, the users’ intimate knowledge of the domain processes and their requirements make them key contributors to ensuring that the domain model aligns closely with real-world application and utility.

In the context of the given scenario, the Use Case "Manage customer information" appears to be a general use case that encompasses the functionalities of adding, deleting, and updating customer information. The specific functionalities are represented by separate use cases, namely "Add new customer", "Delete customer", and "Update customer information".

In UML Use Case diagrams, the «include» relationship should be used when a use case implicitly requires the capabilities of another. However, when the use case is a higher-level description that can be further elaborated into more specific use cases, the «extend» relationship is more appropriate, but in the reverse direction as shown in Option B.

Option B correctly uses the generalization relationship which is not depicted by any arrows or lines but by a whole-part structure, indicating that the specific use cases are a part of the general "Manage customer information" use case.

Option A shows the "Manage customer information" use case extending the specific use cases, which is not correct given the context.

Option C incorrectly uses «include» relationships, implying that the "Manage customer information" use case always requires the included use cases.

Option D has the «extend» relationships backward, which is not aligned with the scenario described.

Therefore, the correct answer is:

B. Option B

Option C shows a UML diagram where a class (One) appears to have an aggregation relationship with itself. In UML, an aggregation is a special type of association that represents a whole-part relationship between the aggregate (whole) and a component part. However, it does not make sense for a class to aggregate itself; such a relationship implies that instances of the same class are parts of each other, which is conceptually invalid.

Let's consider the other options: A) This diagram shows a class contained within another, which is a valid use of nesting classes. B) This diagram shows a composition relationship, which is a form of aggregation with a stronger lifecycle dependency between the whole and the part. This is a valid relationship in UML. D) This diagram shows a class containing two nested classes, one of which contains another nested class. This is also a valid representation of nested classes in UML.

Therefore, the correct answer is:

C. Option C

In UML, Comments are annotations that can be attached to most elements within UML diagrams. Their primary function is not to affect the semantics of the model directly but to provide useful information to anyone reading the model. Comments can help explain or clarify design decisions, make notes about specific parts of the model, or provide any other context necessary for understanding the model better.

The role of Comments in UML is not to enable automatic generation of code comments or to add constraints or semantics to model elements, although they can be associated with model elements to highlight or explain specific attributes or relationships.

References:

• UML 2.x Superstructure Specification: This document describes Comments as a way to provide human-readable descriptions and notes that do not impact the execution or structure of the model but are crucial for documentation and understanding.
• UML 2.x Infrastructure Specification: Further delineates the role of comments in providing clarifications and additional information useful for model interpretation.

In UML, a Class is a template that defines the structure and behavior of objects, whereas a DataType is a type of classifier which specifies a domain of values without identity. Operations (such as money transfers and withdrawals) are behaviors that change the state of an object and, therefore, are defined in Classes rather than DataTypes. This suggests that accounts, which require operations to transfer and withdraw money, should be modeled as Classes.

References:

• UML 2.x Superstructure Specification: Provides definitions for Classes and DataTypes, and details the circumstances under which each should be used. It specifically states that Classes can have operations while DataTypes cannot.
• UML 2.x Infrastructure Specification: This foundational document provides an in-depth explanation of UML modeling constructs, supporting the use of Classes when operations are needed to manage an object's state.

UML 2 Foundation concepts for activity diagrams, there are three valid action notations shown. Here's a breakdown of the elements and why answer D is the most accurate:

• The diagram displays an activity diagram with a main flow and a fork followed by a join.
• Main Flow: This starts with an action labeled "Fill Order".
• Fork: The path splits into two branches after "Fill Order".
• Branch 1: This branch leads to an action labeled "Print Paycheck".
• Branch 2: This branch leads to an action labeled "Send Invoice".
• Join: The two branches converge into a join element.
• Following the Join: An action labeled "End" is present after the join.

Explanation for Valid Actions:

• Fill Order: This clearly represents an action within the activity diagram.
• Print Paycheck: This is another valid action on a separate branch.
• Send Invoice: Similarly, this is an action on the other branch.

Explanation for Why Other Options are Incorrect:

• A. 0: There are clearly multiple actions depicted in the diagram.
• B. 1: There are more than one valid action shown.
• C. 2: While there are actions before the fork, there's also a valid action ("End") after the join.
• E. 4: Counting the join element as an action results in an overcount. Joins represent control flow elements to synchronize multiple paths, not actions themselves.

References

• UML 2.5.1 Specification (Superstructure): Sections on Activity Diagrams and Actions https://www.omg.org/spec/UML/2.5.1/

In UML, visibility of an attribute is determined by the scope of the classifier it belongs to and its visibility markers. The attribute 'v' is marked with a '-' sign, indicating it is private. Being private, it would normally be visible only within the class it is defined in, which is 'S' in this case. However, since 'T' is a subclass of 'S' (as indicated by the generalization relationship, a line with a closed, unfilled arrowhead), it inherits the attribute 'v'. Therefore, 'v' is visible in both 'S' and 'T'.

Option A is incorrect because it does not consider inheritance. Option B is incorrect for the same reason. Option D is incorrect because a private attribute in a class is not visible to the entire package, only to the class itself and its subclasses.

The UML 2.5 specification states that a private member is only accessible within the namespace it is defined (section 7.5.3). Since 'T' is within the namespace of 'S' due to inheritance, 'v' is visible in both.

The diagram fragment shows an instance specification for anEmployee. The different prefixes before each attribute indicate the visibility of that attribute:

• +Public: Visible to everyone.
• -Private: Visible only within the defining class.
• #Protected: Visible to subclasses and package.
• ~Package: Visible to all classes within the same package.

Given these visibility indicators, the attribute with the private visibility is-salary: Real. This means that thesalaryattribute is the one that is hidden outside of thecurrent:Employeeclassifier and cannot be accessed by entities that do not belong to theEmployeeclass.

Therefore, the correct answer is:

C. salary

UML 2 state machine concepts, here's the analysis of the state machine's behavior after the event and the most likely answer:

State Transition Triggered by Event Ev:

The state machine starts in the "Start" state. When the event "Ev" occurs, there's a transition leaving "Start" with a condition "[VAR is equal to 0]".

Value of Local Variable VAR:

The prompt specifies that the value of local variable VAR is equal to zero at the time of the event.

State Transition Evaluation:

Since the condition "[VAR is equal to 0]" is true (given VAR's value is zero), the transition from "Start" to state "State1" is triggered.

Completion of Run-to-Completion Step:

Upon reaching "State1", there are no further outgoing transitions or events to consider. "State1" itself has no exit actions specified. Therefore, the run-to-completion step reaches its end at "State1".

Most Likely Answer:

Based on the analysis above, the most likely answer is:

C. End3

Explanation for Other Options:

• A. End1: There's no direct path from "Start" to "End1".
• B. End2: Similar to option A, there's no transition leading to "End2" when the event occurs and VAR is zero.
• D. Start: The state machine transitions out of "Start" upon the event "Ev". It won't return to "Start" without another transition.

Possible Ambiguity:

It's important to note that state machines can involve complex logic and actions within states. While "State1" appears to be a terminal state in this case, it's conceivable that there could be hidden actions within "State1" that modify VAR or trigger further transitions. The prompt and the provided image don't provide enough information to definitively rule out such possibilities.

Considering the Absence of Mentioned Ambiguity:

Assuming there are no such hidden actions or unspecified behaviors within "State1", then answer C (End3) is the most reasonable conclusion based on the information available in the prompt and image.

In UML 2, a class diagram is used to depict the structure of a system by showing the system's classes, their attributes, operations (or methods), and the relationships among the classes. The constraint{age >= 18}in thePersonclass diagram indicates a condition that must hold true for the instances of thePersonclass whenever they are used in the context of aBankAccount. This constraint is an invariant of thePersonclass that specifies the rule for the attributeage.

Now, let's consider the provided options and explain why option B is correct:

A. The preferred age to open a bank account is 18 years old or older – This statement is incorrect because the diagram does not indicate a preference; it indicates a constraint or a rule.

B. Only customers who are 18 years old or older can open a bank account – This is the correct statement. The{age >= 18}constraint next to theageattribute of thePersonclass signifies that any instance ofPersonassociated with aBankAccountmust be at least 18 years old. SincePersonis connected toBankAccountwith the role namecustomer, this implies that only persons who are at least 18 can be customers of a bank account.

C. The age condition should only hold when the setAge(Integer) function is called – This statement is incorrect because the constraint{age >= 18}is not a condition that applies only when thesetAgeoperation is invoked. Instead, it is a class invariant that must always hold true for any instance ofPerson.

D. An object of Customer with age set to 18 or greater will raise an exception – This is incorrect because the UML diagram specifies a constraint, not an exception condition. The constraint ensures validity, not the raising of an exception.

The answer is verified according to the UML 2 Foundation documents, such as the UML 2.5 specification, where class diagrams and constraints are defined. The specification states that constraints are semantic conditions or restrictions expressed in natural language text or in a machine-readable language that must hold true for the system being modeled (UML 2.5 specification, section 7.9).

In UML, when specifying the value of an attribute in an instance specification (which is what each of these boxes represents), the notation used is generally:

attributeName: Type = Value

Looking at each option provided, we see that they are different representations of numerical values for an attribute namedsalaryof typeReal. Here's how to interpret each representation:

A)-salary: Real = “$10,000.00”- This uses a string representation of the number, which is generally not how numerical values are assigned in UML, especially with the explicit typeReal.

B)-salary: Real = $20,000.00- This is more typical for showing a real number in UML, though the dollar sign is not part of the actual numerical value and should not be included.

C)-salary: Real = 30000.00- This is a correct numeric representation of a real number without unnecessary symbols.

D)-salary: Real = 40,000.00- This is also a correct representation and indeed has the highest numeric value among the options provided.

E)-salary: Real = 500 E 02- This is scientific notation, which is also a valid representation of real numbers in UML. The value represented here is 500 * 10^2, which equals 50,000.00.

After examining each option, the correct answer is D. Option D, because the instancefour:Employeehas the highest value properly assigned to asalaryslot according to the standard UML notation. However, there's a point to be clarified: while UML does not specify formatting of numbers with commas for thousands or currency symbols, it does accept scientific notation. So, if we were strictly interpreting the values as real numbers, Option E would represent the highest numerical value. But considering proper UML formatting and assuming the intent is to use standard decimal notation without currency symbols or commas, Option D is the best answer.

Having all the UML diagrams of a model maintain the same level of detail is typically required by tools that automatically transform the model into other forms, such as code or other types of models. Consistency in the level of detail across different diagrams ensures that automated tools can reliably interpret and convert the UML diagrams without encountering discrepancies that could lead to errors or misrepresentations in the generated outputs. This consistency is crucial for maintaining the integrity of the transformations and for ensuring that the resultant products accurately reflect the intended design and specifications.

In UML 2, a structured class can have internal parts, which are depicted using 'parts' or 'roles' within the class diagram. These internal parts are used to show the composition of the class in terms of contained classes or components. In the context of the question, the structured class named 'System' contains two parts named 'Subsystem1' and 'Subsystem2'.

Option C is the equivalent definition of 'System' in terms of UML 2 notation for several reasons:

• It represents the structured class 'System' with internal parts correctly labeled as 's1:Subsystem1' and 's2:Subsystem2-[ ]', which indicates the role names 's1' and 's2' followed by the class type 'Subsystem1' and 'Subsystem2' respectively. The notation '1..*' after 's2:Subsystem2-[ ]' suggests a multiplicity, meaning that there can be one or many instances of 'Subsystem2' associated with 'System'.
• The compartmentalization within the structured class is indicative of the composition of the 'System', showing that 'Subsystem1' and 'Subsystem2' are integral parts of the 'System'.
• The notation conforms to the standard UML 2 representation for composite structures, as described in the UML 2 Superstructure Specification, where a class can be broken down into its constituent parts within the class rectangle.

This information is verified against the UML 2 Superstructure Specification, which is the authoritative source for UML notation and semantics. Particularly, this aligns with section 9.3.5 on Composite Structures Diagrams, which details the graphical notation for parts and roles within a structured class.

An execution occurrence specification in UML sequence diagrams is represented by a thin rectangle on a lifeline. It shows that an instance is performing an action over a period of time.

In the provided sequence diagram, we can see three such thin rectangles on lifeline 'b', which indicates that there are three execution occurrence specifications.

• One for the message that comes from 'a' to 'b'.
• Another one for the message that 'b' sends to 'c'.
• And the last one for the return message from 'c' to 'b'.

There are no execution occurrence specifications on lifelines 'a' and 'c'.

Therefore, the correct answer is:

D. 3

In UML, a behavioral feature is a feature of a classifier that specifies an aspect of the behavior of its instances. A behavioral feature is implemented (realized) by a method. Operations are a kind of behavioral feature; they are the specifications of transformations or queries that can be requested from an object of the classifier.

Here's why the other options are not correct:

A) "Method" is not a behavioral feature; it is a realization of one. B) "Function" is more of a programming concept than a UML term and would likely be modeled as an operation if it's part of a classifier. D) "Constraint" is not a behavioral feature but a restriction on some aspect of a classifier or a stereotype. E) "Method Invocation" is not a feature; it's an action that invokes a method. F) "Classifier behavior" is a broader concept that defines the behavior characteristic of classifiers as a whole, not a behavioral feature in itself.

Therefore, the correct answer is:

C. Operation

In UML, inherited properties are those attributes that are defined in a superclass and inherited by a subclass. According to UML notation, when a subclass inherits from a superclass, it inherits all the attributes and operations of the superclass unless they are redefined.

Let's examine each option:

A. In Option A, the Customer class shows the attributes name and address repeated from the Person class. This is not necessary in UML to show inheritance and could imply these are different attributes that happen to have the same name.

B. In Option B, the attributes of the Person class are not shown in the Customer class. This is correct as UML assumes that all attributes and operations are inherited by the subclass, and there is no need to repeat them unless they are overridden or extended. In this case, the diagram shows inheritance correctly without redundant representation of inherited properties.

C. In Option C, the inherited properties name and address are explicitly marked as inherited. While it's possible to show inherited properties in this way for clarity, it's not necessary and is less common in standard UML class diagrams.

D. Statement D is incorrect because inherited properties can be shown in a specialized class, although it is not a requirement to do so for the properties to be inherited.

Based on the UML 2 Foundation specification, the correct way to depict inheritance without redundantly listing inherited attributes is shown inOption B.

Enumeration literals in UML are used within an enumeration to define a set of named constants. According to the UML specification:

A. This statement is correct. Enumeration literals are indeed immutable, which means once they are defined within an enumeration, their values cannot be changed.

B. Enumeration literals cannot be anonymous; they must be named so that they can be referenced unambiguously within the model.

C. Enumeration literals can be compared for equality. In fact, this is one of their primary uses, to allow for comparison between different values of an enumerated type to determine if they are the same.

D. Enumeration literal names must be unique within their enumeration. They cannot appear more than once as this would cause ambiguity in references to the literals.

The most accurate statement according to the UML 2 Foundation specification isA: EnumerationLiterals are immutable.

In UML, the aggregation kind 'composite' is one of the two types of aggregation, shared and composite. Composite aggregation, also known as composition, implies that the composed objects do not have a separate lifecycle from the owner object and are parts of the whole. This is in contrast to shared aggregation (aggregation), where the parts can be shared with different owners and have their own lifecycle.

Let's look at the options:

A. Composite aggregation implies ownership and is related to, but not equivalent to namespace containment. Namespace containment is more about the scope for named elements rather than lifecycle management.

B. While it's true that instances of the composed object's type are often associated only with the composite object, the key aspect of composite aggregation is not just the exclusive context but the lifecycle dependency, which is not captured in this option.

C. This option is correct because, in UML, composite aggregation (composition) implies that the parts are existentially dependent on the whole. When the composite (whole) object is destroyed, so are all of its parts, indicating a strong lifecycle dependency between the composite object and its composed parts.

D. This option describes a relationship more akin to set theory than UML composition. In UML, composite aggregation doesn't deal with subsets and unions in the context of set theory.

Thus, the most accurate answer, according to the UML specification regarding composite aggregation, isC: When the Property's composite object ceases to exist, all of its composed objects also cease to exist.

• The execution starts from activity A (as there's no incoming transition).
• From A, there's only one outgoing transition leading to activity E.
• Following the transition from E, the flow reaches activity C.
• There are no further outgoing transitions from C, signifying the end of the valid trace.

Explanation of Why Other Options are Incorrect:

• A. E waits for an Event: The diagram doesn't show an explicit wait event associated with activity E. While an event might trigger the initial start of the activity A, the provided trace (A, E, C) focuses on the control flow between the activities themselves.
• B. E is always executed faster than B: There's no basis to establish a timing relationship between E and B based solely on the structure of the diagram. The order of execution is A, E, C, but their relative speeds cannot be determined from this information.
• D. C waits for tokens on both incoming edges: Activity C has two incoming transitions, but the concept of waiting for tokens on both edges simultaneously doesn't apply here. Since the flow reaches C from activity E, only the transition from E provides the token needed to enable C's execution.

Trace vs. Path

It's important to distinguish between trace and path in an activity diagram:

• Trace: A specific sequence of activity executions along a feasible path.
• Path: A possible route through the activity diagram, which may or may not be a valid trace depending on the presence of decisions or loops.

In this case, the answer focuses on the valid trace A, E, C, which represents a confirmed sequence of activity executions based on the transitions in the diagram.

References

• UML 2.5.1 Specification (Superstructure): Sections on Activity Diagrams https://www.omg.org/spec/UML/2.4/Superstructure/PDF

In a UML system, the state machine associated with an object becomes active and ready to process events as soon as the object's initialization process is complete. Here's why:

• Object Creation and State Machines: When an object is created, its associated state machine is instantiated along with it. This means the state machine's structural elements (states, transitions, etc.) are established.
• Initialization and the Initial State: During the object's initialization phase, essential attributes and relationships might be set up, and the state machine enters its designated initial state.
• Event Readiness: Once initialization is complete, the object and its state machine are considered "operational" and can respond to events as defined by the state machine's logic.

Why Other Options are Incorrect:

• A. by the time the last state ends: State machines often don't have a designated "last" state. Their execution is based on events and can continue indefinitely. Additionally, a state machine can be ready to handle events long before ending.
• B. immediately after the sequence diagrams start: Sequence diagrams illustrate interactions between objects, but they don't dictate the exact timing of object creation or state machine readiness in the overall system.
• D. when all objects in the system are ready to receive events: While system-wide coordination might be necessary, an individual object's state machine readiness is dependent on its own initialization, not on the state of every other object.

References:

• UML Specification (Superstructure) Version 2.5.1: Specifically, sections covering state machines (https://www.omg.org/spec/UML/2.5.1).
• Practical guides to UML and object-oriented modeling often discuss object creation and state machine lifecycles.