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

[EX Q]: Which Chuck Berry song is performed by Marty McFly at the end of the film Back to the Future?
[EX A]: back to the future

[EX Q]: What American swimmer won eight gold medals at the 2008 Olympics?
[EX A]: 2008 summer olympics

[EX Q]: Who was the father of Alexander the Great?
[EX A]:
alexander the great