Which formula does Google use to rank keyword-targeted ads on Google Search ?

  A)  (Maximum cost-per-click (CPC) bid + Daily Budget) / Quality Score

  B)  Maximum cost-per-click (CPC) bid x Quality Score

  C)  (Maximum cost-per-click (CPC) bid x Quality Score) / Daily Budget

  D)  Maximum cost-per-click (CPC) bid only