Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.

[EX Q]: What is the SI unit of capacitance?
[EX A]: capacitance

[EX Q]: To which country do the Chatham Islands belong?
[EX A]: chatham islands

[EX Q]: Which British composer wrote the opera Troilus and Cressida?
[EX A]:
troilus and cressida