This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Forensic Medicine
[{'content': 'Black gunpowder contains all of the following, except: PGI 06; Punjab 09 \nSelect and explain. \nA. Potassium nitrate, B. Lead peroxide, C. Charcoal, D. Sulfur', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Lead peroxide', 'role': 'assistant'}]