Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

What name was given to the 1950-60s mainstream country music style of artists including Patsy Cline, Tammy Wynette, Jim Reeves, and Charlie Rich?
charlie rich

Which TV character has sisters called Daisy and Rose?
daisy

Name the pioneering Game Theory US mathematician featured in the film A Beautiful Mind?

a beautiful mind