A use case is fundamentally a description of how users will interact with a system to achieve a specific goal. It captures the functional requirements of a system by focusing on the user’s perspective and detailing the steps taken in a typical interaction. This helps ensure that the system meets user needs and aligns with business objectives.
Use cases typically include various components, such as the actors involved (users or other systems), the preconditions that must be met before the interaction, and the sequence of actions taken to reach the desired outcome. By concentrating on user interactions, use cases provide a clear and concise narrative that guides the development and validation process, ensuring the resulting solution addresses actual use scenarios.
Contexts for other options are more related to project planning and documentation rather than the specific interactions users have with a system. Budget estimates pertain to financial planning, technical specifications focus on the technical aspects of the system's design, and project risks are concerned with uncertainties that might impact project outcomes. None of these elements capture the essence of user interaction in the way that a use case does.