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

[EX Q]: What is the country of origin of the cheese called caerphilly?
[EX A]: caerphilly cheese

[EX Q]: Mar Chiquita (Cordoba) is the largest natural salt lake in which South American country?
[EX A]: mar chiquita lake

[EX Q]: Michael J Fox played which character in the Back to the Future trilogy (1985-1990)?
[EX A]:
back to the future