Negative keywords can help advertisers refine the targeting of their ads, and potentially increase:96

  • the number of relevant Display Network Placements
  • their campaigns daily budget recommendations
  • the clickthrough rate (CTR) of their ads
  • the number of impressions served

The correct answer is:

  • the clickthrough rate (CTR) of their ads

Explanation: Negative keywords are an important part of every campaign because they help make sure that your ads appear only to people looking for what you offer. This added level of control can help you increase your clickthrough rate (CTR), reduce your average cost-per-click (CPC), and increase your ROI.

Read more here: https://support.google.com/adwords/answer/105671?hl=en