Question: Was the death of Heath Ledger caused by his work on The Dark Knight?, Answer:No, Description of The Dark Knight (film): 2008 film directed by Christopher Nolan, Fact1: Heath Ledger accidentally overdosed on prescription medication., Fact2: Heath Ledger's overdose led to his death. 
Step1: What was the cause of Heath Ledger's death?, Step2: Is #1 related to his work on the The Dark Knight?, Wikipedia page for step 1: Heath Ledger, Wikipedia page for step 2: , not_definitive_answer: False, incorrect_answer: False