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 group of the 1970's featured Tony Iommi on guitar, Geezer Butler on bass and Bill Ward on drums?

SOLUTION: geezer butler

PROBLEM: Which Roman Emperor was the son of Germanicus and Agrippina the Elder?

SOLUTION:
agrippina the elder