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

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

Ex Output:
charles darwin

Ex Input:
Who was re-elected Prime Minister of Canada in May 2011?

Ex Output:
prime minister of canada

Ex Input:
Who directed the 2003 film starring Ewan McGregor, Billy Crudup and Albert Finney called Big Fish?

Ex Output:
big fish