What is the benefit of having multiple ads in an ad group?

172) What is the benefit of having multiple ads in an ad group?

   A)  AdWords will automatically match each ad to the keywords it's most relevant to
   B)  Ads are only eligible to show ad extensions if there are more than one ad in that group
   C)  Ads are only eligible to show at the top of the page if there are more than one ad in that ad group

   D)  AdWords will automatically rotate your ads and show the best performing ones more often