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

Which Chuck Berry song is performed by Marty McFly at the end of the film Back to the Future?
back to the future

Richard Block and David Quayle founded which British-based DIY retailing company in 1969?
david quayle

US President Bill Clinton belonged to which political party?

bill clinton