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 only nation state of the Commonwealth of Nations on the mainland of South America?

SOLUTION: commonwealth of nations

PROBLEM: The Trinity test site, outside of Alamogordo, NM, saw the first test of the atomic bomb on July 16, 1945. Headed by J. Robert Oppenheimer, what was the name of the project that developed the bomb?

SOLUTION: j. robert oppenheimer

PROBLEM: Which Charles Dickens novel was set during the Gordon riots?

SOLUTION:
charles dickens