You create an application by using Microsoft Visual Studio .NET 2008 and the .NET Framework 3.5. The application will be used by multiple types of users. The application will also interact with external applications. You need to design the interaction among the application, the users of the application, and the external applications. What should you do?

A.
Create a class diagram.

B.
Create a timing diagram.

C.
Create a Use case diagram.

D.
Create a state machine diagram.