The correct answer is:
choosing five CDs where not all of them are pop
Step-by-step explanation:
The complement of an event is the set of outcomes that are not the event in question. In this case, the event is April choosing 5 CDs and all of them being pop. The complement then, the set of outcomes that are not April choosing all 5 pop CDs, means at least 1 of them would not be pop. This would be enough to make it the complement.