An advertiser wants to increase clickthrough rate (CTR). Which would help to eliminate irrelevant impressions

An advertiser wants to increase clickthrough rate (CTR). Which would help to eliminate irrelevant impressions?

A) Assign unique keyword URLs to each keyword
B) Evaluated the site design for improvements
C) Add negative keywords to the ad group
D) Add more relevant keywords to the ad group

Answer - Add negative keywords to the ad group