Google Makes Many Recommendations for Google AdWords Users for Direct

Google makes many recommendations for Google AdWords users for direct response campaigns. One of the recommendations Google makes is to implement cost-per-click bidding so that you only pay when people click your ad. What other reason is valid for using the cost-per-click bidding?

A) If you want to include video overlays ads, you must use cost-per-click bidding.
B) If you want to be included in Google Content Network, you must use cost-per-click bidding.
C) If you are creating a display ad, you must use cost-per-click bidding.
D) If you want to use the Conversion Optimizer tool, you must use cost-per-click bidding.