TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: In which book of the Bible are the Ten Commandments first mentioned?

SOLUTION: bible

PROBLEM: What was the last silent film in which Chaplin's little tramp appeared?

SOLUTION: chaplin

PROBLEM: What position has Boris Johnson held from 4 May 2008?

SOLUTION:
boris johnson