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

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

Example Input: The film Schindler's List was based on whose Booker Prize winning novel of 1982?
Example Output: schindler's list

Example Input: Which TV family live at 742 Evergreen Terrace?
Example Output:
the simpsons house