When using cost-per-acquisition (CPA) bidding, an advertiser bids using a maximum CPA and pays by:

When using cost-per-acquisition (CPA) bidding, an advertiser bids using a maximum CPA and pays by:

  • Conversion
  • Click
  • Viewthrough
  • Impression

The correct Answer is:

  • Conversion

Explanation: Target CPA is an automated bid strategy that sets bids to help get as many conversions as possible at the target cost-per-acquisition (CPA) you set. Target CPA is available as either a standard strategy or as a portfolio strategy

Read more here: https://support.google.com/adwords/answer/6268632?hl=en&rd=1