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

[Q]: What is the main river of Brazil?
[A]: brazil


[Q]: Which brothers own the Daily Telegraph?
[A]: the daily telegraph


[Q]: Iron Maiden, Saxon, Def Leppard, Van Halen, Led Zeppelin and Black Sabbath are associated with what style of music?
[A]:
black sabbath