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

[EX Q]: Which chemical element is named after the Latin for Copenhagen where it was discovered?
[EX A]: copenhagen

[EX Q]: Which popular Doctor Who villains, it was revealed in 2011, are to be given 'a rest' by scriptwriters?
[EX A]: doctor who

[EX Q]: Which river with a vast delta to the South china Sea rises as the Za Qu in Tibet?
[EX A]:
china