Which statement best describes a call event?

Which statement best describes a call event?

• A. Represents the receipt of a request to invoke an operation in a target structure
• B. Represents the return of a previously invoked operation
• C. Represents a time event
• D. Represents a signal to initialize a substate

Answer: (A)

A call event represents the moment one component asks another to perform an operation. It captures the receipt of a request to invoke a specific operation on a target structure, typically carrying any needed arguments. This is how inter-object behavior is modeled: a trigger arrives that tells the recipient to start executing that operation. In contrast, a return event signals that the operation has finished and its result is sent back; a time event is driven by clock timing; and initializing a substate is not about calling an operation but about entering the appropriate part of a composite state.

A call event represents the moment one component asks another to perform an operation. It captures the receipt of a request to invoke a specific operation on a target structure, typically carrying any needed arguments. This is how inter-object behavior is modeled: a trigger arrives that tells the recipient to start executing that operation. In contrast, a return event signals that the operation has finished and its result is sent back; a time event is driven by clock timing; and initializing a substate is not about calling an operation but about entering the appropriate part of a composite state.