When a group of people share common characteristics, such as gender or ethnicity, the group is labeled a: ?

Can someone read this article and tell me the 1) key ideas and 2) one key quote (copy and paste the link the article is not to long at all)from

What are policymakers trying to do by using the media to deliver specific messages to citizens?

Which supreme court dressed the second a. presser v. illinois b. quilici v. the village of morton grove c. united states v. cruikshank d. united states v. miller