The correct answer is: C. means that the upper module has the capability of calling the lower module.
A couple is a relationship between two modules in a program. It is represented by a line joining the two modules. The upper module is called the caller, and the lower module is called the callee. The caller can call the callee by executing a function call statement.
Option A is incorrect because a couple is not a data item. A data item is a piece of information that is stored in memory. A couple is a relationship between two modules.
Option B is incorrect because a couple is not represented by a line joining two modules. A couple is represented by a line with an arrow pointing from the caller to the callee.
Option D is incorrect because a couple does not mean that the upper module has the capability of calling the lower module. The upper module can call the lower module, but it does not have to.
Option E is incorrect because there is only one correct answer.