Choose the correct answer: Consider the following interaction diagram.

In UML sequence diagrams, an execution specification is represented by a thin rectangle along a lifeline. It shows where in time the execution takes place, starting with the initiation of an operation or process and ending when that process is complete.

In the interaction diagram provided, we can see an execution specification on the lifelinep1: Pthat starts after the message corresponding to point 3 is received and ends just before the message corresponding to point 5 is sent. This means the execution specification is bracketed by points 3 and 5.

Points 1 and 2 represent message sends, 1 and 4 could represent a message send and receive for the same message, which doesn't typically represent the full execution specification. Points 2 and 3 don't represent a logical start and end of an execution specification because they're on different lifelines.

Therefore, the correct answer is:

D. 3, 5