TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: Krist Novoselic and Dave Grohl were two thirds of which band, formed in Aberdeen (Washington State) whose albums include Bleach and In Utero?

SOLUTION: dave grohl

PROBLEM: Who wrote the novels About A Boy, How To Be Good and High Fidelity?

SOLUTION: how to be good

PROBLEM: What is the biggest city in Catalonia?

SOLUTION:
catalonia