Why is average view frequency important to measure?

A) It lets you continually track conversions
B) It tells you how many people are viewing the ad
C) It shows you how engaged people are with the ad
D) It shows how often the average person sees or interacts with the ad

The correct answer is:

D) It shows how often the average person sees or interacts with the ad

Explanation: The typical number of times that someone viewed your ad over a given time period. For example, if your video ad’s average view frequency is 1.49, it means that someone viewed your ad about one and a half times during a specific period. Ideally, the average view frequency should be closer to 1 because, typically, people don’t want to view ads more than once.

Read more here: https://support.google.com/partners/answer/6024272?hl=en