TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: Grace Anna Goodhue was the wife of which US President?

SOLUTION: grace coolidge

PROBLEM: Cinder Cone, composite, and shield are all types of what?

SOLUTION: cinder cone

PROBLEM: Of which 1969 film was 15-year-old Billy Casper the central character?

SOLUTION:
billy casper