The AdWords system will calculate the effective cost-per-thousand impressions (eCPM) for an ad entering into an auction for the Google Display Network when there are:
A) both cost-per-click (CPC) and cost-per-acquisition (CPA) ads entering the auction
B) both cost-per-thousand impressions (CPM) ads entering the auction
C) only cost-per-click (CPC) ads entering the auction
D) both CPM and CPC ads entering the auction