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

[Q]: Who was the scheming wife of the Roman emperor Claudius?
[A]: claudius


[Q]: Which river begins in the Rocky Mountains in south-west Colorado, crosses New Mexico and forms the border between Mexico and the USA before reaching the Gulf of Mexico?
[A]: new mexico


[Q]: Who released an album in May 2009 called 21st Century Breakdown?
[A]:
21st century breakdown