What type of information does a class diagram represent?

A class diagram is a key component of object-oriented modeling that illustrates the static structure of a system, capturing the relationships and attributes of the various classes and objects within that system. It focuses on the organization of classes, including their properties, methods, and the connections between them, such as associations, inheritances, and dependencies. By providing a visual representation of classes and their relationships, class diagrams help developers understand how different parts of the system interact at a structural level, facilitating better design and organization of the software architecture.

In contrast, the other options relate to different aspects of system design and modeling. Dynamic interactions are often represented through sequence or activity diagrams, functional requirements focus on what the system should do (typically captured in use case diagrams), and user interactions might be documented in UI mockups or user journey maps. Thus, the primary role of a class diagram is to define and showcase the static structure, making it an essential tool for understanding the foundational elements of a system's design.