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

[EX Q]: Albion is the oldest known name for which nation?
[EX A]: albion

[EX Q]: What was the first Apollo mission to leave Earth orbit and orbit the moon, in 1968?
[EX A]: apollo

[EX Q]: Which is the most heavily populated city in China?
[EX A]:
china