What does 'Use Case Modeling' primarily capture?

'Use Case Modeling' primarily captures functional requirements through interactions with users. This technique focuses on identifying the specific ways in which end users will interact with a system or application to achieve particular goals. It outlines various scenarios involving user actions and system responses, depicting the functionalities that the system must provide to meet user needs.

Use Case Modeling serves as a tool for stakeholders to understand how the system will function from an end-user perspective, ensuring that all necessary capabilities are documented and aligned with the users’ expectations. This technique emphasizes the "what" aspect of the system's functionalities, portraying a clear picture of user-system interactions required to fulfill various tasks.

The other options represent different areas of project management and requirements gathering that are not the central focus of use case modeling. While non-functional requirements, project timelines, and budget estimates are crucial components of project planning and development, they do not capture the specific functional requirements through user interactions as effectively as use case models do.