In requirements engineering, a use case is best described as:

• A. The sequence of interactions between users and a system to achieve a goal.
• B. The hardware requirements to run a system.
• C. A summary of organizational policies.
• D. A training plan for end users.

Answer: (A)

Use cases describe how a user interacts with a system to achieve a specific goal. They outline the sequence of user actions and the system’s responses, capturing the steps needed to reach a successful outcome from the user’s perspective. This focus on the interaction flow and the resulting behavior makes use cases a practical way to specify functional requirements and guide design and testing. The other options miss this interaction-oriented view: hardware requirements concern the tech needed to run the system, organizational policies cover rules and governance, and a training plan focuses on educating users, not the step-by-step interactions to achieve a goal.