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

Ex Input:
Aaron Copeland wrote a ballet about which American folk hero?

Ex Output:
aaron copeland


Ex Input:
What currency is used on Christmas Island?

Ex Output:
christmas island


Ex Input:
Which American Nobel Laureate wrote 'The Sound And The Fury' and 'As I Lay Dying'?

Ex Output:

as i lay dying