Based on the Concept of Aperture, What Is the Goal

Based on the concept of aperture, what is the goal of media planning?

A) to get the broadest reach at the lowest cost
B) to get the highest frequency at the lowest cost
C) to get the broadest reach and highest frequency at the lowest cost
D) to reach the right people at the right time with the right message
E) to reach as many people as possible within the constraints of the media budget