In Media Metrics, Frequency Is Which of the Following

In media metrics, frequency is which of the following?

A) the total number of people who will be exposed to an ad placed in one media vehicle
B) the percentage of people who will be exposed to an ad more than once
C) the percentage of people who will be exposed to the media vehicle
D) the number of times a person in the target group will be exposed to an ad
E) the total number of ads in one advertising campaign