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

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

The Neil Simon plays The Prisoner of Second Avenue and Brighton Beach Memoirs are set in which city?
brighton beach memoirs

84 Charing Cross Road is a book based on 20 years of correspondence between which New York writer and Frank Doel, an antiquarian bookseller in London?

84, charing cross road