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

What is the capital of the American state of Delaware Boise, Dover or Jefferson City?
delaware

Which is the only Avril Lavigne song to have reached No.1 in the US Billboard Chart?
avril lavigne

The film Schindler's List was based on whose Booker Prize winning novel of 1982?

schindler's list