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]: Which alliteratively-named politician served as Abraham Lincoln's Vice-President between 1861 and 1865?
[EX A]: abraham lincoln

[EX Q]: Who wrote `A Brief History Of Time`?
[EX A]:
a brief history of time