Which of the Following Is a Defining Characteristic of Google's

Which of the following is a defining characteristic of Google's sponsored links?

A) The advertisers do not have to pay Google.
B) As in the case of banner ads, advertisers pay just for being included in the search results.
C) The amount that an advertiser owes for each click-through is not actually set by Google but it is determined in an auction.
D) The amount that an advertiser owes for each click-through is set by Google.
E) The amount that an advertiser owes for each click-through is set by the IAB.