(A) Callout Extensions
(B) Structured Snippet Extensions
(C) Review Extensions
(D) Action Extensions
Action Extensions allow you to use a Call To Action button to your ads which can lead to higher clicks on your ads. You will be charged as Cost Per Click if a user clicks on the Action extension. You can use the Action extension with other ad extensions including Sitelinks.
This question is a part of the Microsoft Advertising Certified Professional exam. You can find all the answers with detailed explanation for this exam in the Microsoft Advertising Certified Professional exam page.