Which best practice is advisable when optimizing ad groups within a placement targeted display campaign?

Q. Which best practice is advisable when optimizing ad groups within a placement targeted display campaign?

A. Target a broad collection of placements with a single ad group

B. Create a separate ad group for each placements

C. Move automated and managed placements into separate ad groups

D. For each adgroup, target groups of placements with similar themes

Correct Answer is:

D. For each adgroup, target groups of placements with similar themes