Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
--------
Question: Who won the Women's Singles at the 2015 Australian Open Tennis Championships?

Answer: the championships, wimbledon


Question: In which country did the dance The Czardas originate?

Answer: csardas


Question: Who played 'Marty McFly' in the 'Back To The Future' films?

Answer:
back to the future