Which feature distinguishes location extensions from regional and customized campaign targeting?

Which feature distinguishes location extensions from regional and customized campaign targeting? 

A) Location extensions will appear when a user located near the advertised business searches on relevant terms. 
B) Customized campaign targeting determines which address appears below the ad.
C) Location extensions will appear when an advertiser has targeted a specific region or location
D) Customized campaign targeting is required in order to enable location extensions