instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
Which Nation does Aston Villa Goalkeeper Brad Guzan represent?
answer:
brad guzan


question:
Chris Martin is the lead singer with which band who had several hits in the 2000s?
answer:
chris martin


question:
Who was the main character in Sir Arthur Conan Doyle's novels A Study In Scarlet, The Sign of Four and The Hound of the Baskervilles?
answer:

the hound of the baskervilles