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

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

A: back to the future
****
Q: Which singer provides the voice for Chef in South Park?

A: chef
****
Q: What is the largest of the Balearic islands?

A:
balearic islands
****