How is an instance of a case represented in Content Engine?

How is an instance of a case represented in Content Engine?
A . The case custom object, task objects, note objects, document objects
B . The case type object, case folder object, task objects, document objects, note objects
C . The case folder object, task objects, note objects, document objects, audit history objects
D . The case folder object, task objects, task step objects, document objects, note objects, audit history objects

Answer: C