instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
Which 20th century British prime minister had the longest surname ?
answer:
prime minister of the united kingdom

question:
What is the capital of the American state of Delaware Boise, Dover or Jefferson City?
answer:
delaware

question:
What city hosted the 2007 World Athletics Championships?
answer:
2007 world championships in athletics