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 main river of Brazil?

SOLUTION: brazil

PROBLEM: What is the capital city of Colombia?

SOLUTION: colombia

PROBLEM: The 2004 film 'The Aviator' starring Leonardo DiCaprio is a biopic of whom?

SOLUTION:
the aviator