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

Ex Input:
What was the computer's name in 2001: A Space Odyssey?

Ex Output:
2001: a space odyssey

Ex Input:
Which biologist was known as Darwin's Bulldog?

Ex Output:
charles darwin

Ex Input:
What are chlorine, bromine and iodine?

Ex Output:
chlorine