instruction:
Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
question:
Which is the only Avril Lavigne song to have reached No.1 in the US Billboard Chart?
answer:
avril lavigne

question:
Which strong man appears in the Bible in the Book of Judges?
answer:
book of judges

question:
Which British author co-wrote the script for the 1968 film 'Chitty Chitty Bang Bang'?
answer:
chitty chitty bang bang