Which is the best tip for optimizing a trueview video for viewer engagement?
a. look at engagement rate for targeting and focus on the methods with the highest view through rate
b. run both an in-stream and a video discovery version of the ad increase each target group's bid by 100%
c. add exclusions to the campaign

(A) Look at engagement rate for targeting and focus on the methods with the highest view through rate

Explanation:

TrueView video enables to post ads in social sites however it is paid by the sponsor only if the ad is viewed fully or in some cases it is viewed only upto 30s of the total size of the video.

So in order to have a larger viewer engagement it is necessary for it to focus on the methods which would garner it highest views.

So option A is correct.

Option B and c are not correct these options would not cater to the needs of the viewer.