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 is the name of the main thoroughfare in Barcelona, which runs from the Placa de Catalunya to the sea?

SOLUTION: barcelona

PROBLEM: Who has taken over the TV role of Doctor Who, from actor David Tennant?

SOLUTION: doctor who

PROBLEM: Which US singer released a 1962 album entitled 'Pot Luck'?

SOLUTION:
album