What is the primary purpose of an activity diagram?

• A. A static structure diagram
• B. A dynamic view of the system that expresses sequences of behaviors and event occurrences over time
• C. A data model of entities
• D. A deployment map

Answer: (B)

Activity diagrams capture how a process actually unfolds, focusing on the dynamic behavior of a system over time. They show the sequence of activities, the events that trigger transitions, and how decisions or parallel paths influence the flow. This helps you understand not just what components exist, but how work moves through the system in different scenarios, including branching and synchronization points.

In contrast, a static structure diagram maps the organization of the system at rest—how classes or components relate to each other. A data model of entities outlines the data objects and their relationships. A deployment map shows where software runs on hardware. Those diagrams describe structure or deployment, not the step-by-step behavior or timing of operations, which is why they’re not the primary purpose of an activity diagram.