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

[EX Q]: Who had a hit album in 2010 with Can't Be Tamed?
[EX A]: can't be tamed

[EX Q]: Which is the only Avril Lavigne song to have reached No.1 in the US Billboard Chart?
[EX A]: avril lavigne

[EX Q]: Agrava, Cephlon and Virn are all fictional planets in which BBC science fiction television series?
[EX A]:
science fiction on television