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

[EX Q]: In 2013 Yahoo purchased which pictures and video microblogging website business that was founded in 2007 in New York City by David Karp?
[EX A]: yahoo!

[EX Q]: In which shipping forecast area are the Channel Islands?
[EX A]: channel islands

[EX Q]: Until Tony Blair, which of Britain's Labour Prime Ministers was in office for the longest overall time?
[EX A]:
britain