TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: What was the last silent film in which Chaplin's little tramp appeared?

SOLUTION: chaplin

PROBLEM: What's the name of Doctor Who's home planet ?

SOLUTION: doctor who

PROBLEM: What is the main grape used in the production of Chianti wine?

SOLUTION:
chianti