Only those students who maintain 2.5 grade point averages are allowed

The first step for any main point question, CR or RC, is to identify the main point. You can identify a main point by fact that other sentences in the statement will support the main point.

The first sentence gives us the GPA requirement. The second sentence's statement that Amy is the tennis captain and therefore must have a 2.5 doesn't support the GPA requirement for participation. Rather the fact that Amy must have at least a 2.5 is a result of the GPA requirement in the first sentence.

As such, the main point will be the second sentence. All we need now is a restatement of the second sentence.

A) Restates first sentence
B) Outside the scope of the question. Being the tennis captain may mean Amy is a good tennis player but, as Amy's skill is never mentioned in the question, this choice will be wrong.
C) Outside the scope. Lowering the GPA requirement is never mentioned in the question.
D) Summarizes the second sentence.
E) Leaves open multiple outcomes. We are never given the reason Amy was made captain in the question. All we know is that Amy's GPA is 2.5 or above. If her GPA is 2.6 and it falls to 2.5, then she is still eligible for the team and would not lose her position. If it is 2.5 and it falls to 2.49, then she would lose the position. Whenever there is multiple possibilities from an CR answer choice, the answer will almost always be wrong.

As a result, D is the correct answer. For CR questions, the idea to remember is that the answer will be reinforced within the question statement. Any answer choice that can't be tied back to information in the question statement will be wrong.