All of the following are metrics for measuring online ad effectiveness EXCEPT
(A) click-through rate
(B) cost per click
(C) page view
(D) pay per click
(E) pop-under
Answer: The correct answer is E. A pop-under is an online ad that opens behind the Web browser window that is open, but doesn't show up until after all other windows have been closed. A pop-under ad is not a measurement tool, so it is the correct answer to the question.