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

[EX Q]: Formerly known as Sky Dome, Rogers Centre is home to what American League baseball team, the only MLB team located outside the United States?
[EX A]: american league

[EX Q]: Carpo and Elara are moons of which planet?
[EX A]: elara

[EX Q]: Danny O'Donoghue was a judge on the TV show 'The Voice'; he is the singer with which group?
[EX A]:
danny o'donoghue