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

[Q]: Who played the character Gene Hunt in the UK TV series 'Life on Mars' and 'Ashes to Ashes'?
[A]: life on mars


[Q]: Krist Novoselic and Dave Grohl were two thirds of which band, formed in Aberdeen (Washington State) whose albums include Bleach and In Utero?
[A]: dave grohl


[Q]: In which opera do the characters 'Annina', 'Alfredo Germont' and 'Duophol' appear?
[A]:
alfredo germont