TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: Which British composer wrote the music used as the theme for Desert Island Discs  He also wrote the Dambusters march and the Knightsbridge march.?

SOLUTION: the dam busters

PROBLEM: Which play and film was adapted from a story by Christopher Isherwood and later adapted as the musical and film Cabaret?

SOLUTION: cabaret

PROBLEM: David Balfour and Alan Breck are characters in books by which author?

SOLUTION:
david balfour