Question: The type of the novel the 2012 American coming-of-age drama film The Perks of Being a Wallflower is based on is a novel written in what form?
Sentence (from "The Perks of Being a Wallflower (film)"): An adaptation of the 1999 epistolary novel of the same name, it was written and directed by the novel's author, Stephen Chbosky.
Relevant evidence: Yes