instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
Which British Prime Minister married Clementine Hozier on September 12th 1908?
answer:
clementine churchill

question:
Aragon and Castile joined to form which country?
answer:
aragon

question:
Ride of the Valkyries is the official quick march of which branch of the British Army?
answer:
british army