What best describes Enhanced Cost-Per-Click (ECPC)

75)  What best describes Enhanced Cost-Per-Click (ECPC)

  A)  ECPC is a separate bid set for ad groups using the Conversion Optimizer
  B)  ECPC is a CPC bidding feature that automatically bids more aggressively in auctions more likely to result in a conversion
  C)  ECPC is a Quality Score boost for advertisers using ad extensions

  D)  ECPC is the discount applied to your Max CPC to determine actual CPC