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

Ex Input:
Which group of the 1970's featured Tony Iommi on guitar, Geezer Butler on bass and Bill Ward on drums?

Ex Output:
geezer butler


Ex Input:
Who wrote the poem Elegy Written in a Country Churchyard?

Ex Output:
elegy written in a country churchyard


Ex Input:
What famed documentarian, a staple of PBS, has produced films on The Civil War, Baseball, Jazz, World War II, and National Parks?

Ex Output:

jazz