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

[EX Q]: Physics. What is the SI unit for amount of substance?
[EX A]: amount of substance

[EX Q]: The towns od Grimsby and Cleethorpes are in which English county?
[EX A]: grimsby

[EX Q]: Which UK actress gave an acclaimed performance as a ballet teacher in the film Billy Elliott?
[EX A]:
billy elliot