Target cost-per-acquisition (CPA), which factors in auction-time signals including device, location, time of day, remarketing list, language, and operating system, automatically optimizes bids across:

Target cost-per-acquisition (CPA), which factors in auction-time signals including device, location, time of day, remarketing list, language, and operating system, automatically optimizes bids across:

  • search and display inventory to help advertisers reach their desired cost-per-install goal
  • search and display inventory to help advertisers reach their desired cost-per-impression goal
  • search and display inventory to help advertisers reach their desired cost-per-click (CPC) goal
  • search inventory to help advertisers reach their desired cost-per-install goal

Correct answer is:

  • search and display inventory to help advertisers reach their desired cost-per-install goal

Explanation: Market to people, not devices: Google can measure many of your customers’ valuable actions, regardless of which device or channel drove it. Measure mobile actions that users take (e.g., purchase, call, app download, directions) across channels (e.g., search, video, display, in-app), and across devices.AdWords automatically takes into account dozens of signals (e.g., location, time of day, CTR, device) and adjusts bids accordingly across search and display inventory to help advertisers hit desired cost-per-install goals.
Read more here: https://support.google.com/partners/answer/6208446