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

Ex Input:
What's the name of Doctor Who's home planet ?

Ex Output:
doctor who

Ex Input:
Which motor manufacturer produces the Duster model?

Ex Output:
dacia duster

Ex Input:
Who joined the Eggheads team in 2008, having won Are You An Egghead?

Ex Output:
eggheads