TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: The Cato Street Conspiracy was a plot to kill which British Prime Minister?

SOLUTION: prime minister of the united kingdom

PROBLEM: Which popular Doctor Who villains, it was revealed in 2011, are to be given 'a rest' by scriptwriters?

SOLUTION: doctor who

PROBLEM: Brazil is the largest country on which continent?

SOLUTION:
brazil