Answer :
A use case diagram is a UML technique for visually representing the interaction between users and a system, used as part of a system's design to clarify user interactions and system functionality.So the correct option is c-use case diagram.
A use case diagram is a Unified Modeling Language (UML) technique that visually represents the interaction between users and an information system. This type of diagram is a part of systems design, which includes various elements needed to build a system. Among these elements are diagrams that outline and explain parts of a system or process. In UML, a use case diagram serves as a tool to depict the roles of users (actors) interacting with the system and to map out the system's functionality from the user's perspective. It simplifies the representation of a system, highlighting the important components and connections, which aids in understanding real-world aspects of the system's use.So the correct option is c-use case diagram.