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

Ex Input:
Which English king was the son of Edward, the Black Prince?

Ex Output:
edward, the black prince


Ex Input:
Everything Changes, Beautiful World and Circus are all albums released by which British band?

Ex Output:
beautiful world


Ex Input:
What was the name of the changeling on Deep Space Nine?

Ex Output:

star trek: deep space nine