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

Ex Input:
The film Schindler's List was based on whose Booker Prize winning novel of 1982?

Ex Output:
schindler's list

Ex Input:
Ride of the Valkyries is the official quick march of which branch of the British Army?

Ex Output:
british army

Ex Input:
'Dookie' and '21st. Century Breakdown' are albums by which American rock band?

Ex Output:
21st century breakdown