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: Physics. What is the SI unit for amount of substance?

SOLUTION: amount of substance

PROBLEM: Roger Fry, Vanessa Bell, and Duncan Grant were part of which English art movement in the 1920's and 30's?

SOLUTION:
duncan grant