This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Mechanical injuries, Subject name: Forensic Medicine
[{'content': 'Black gun powder composition - \nSelect and explain. \nA. Carcoal 60% + Potassium nitrate 20% + sulphur 20%, B. Charcoal 25% + Potassium nitrate 70% + sulphur 05%, C. Charcoal 15% + Potassium nitrate 75% + sulphur 10%, D. Charcoal 65% + Potassium nitrate 20% + sulphur 15%', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The synopsis of forensic medicine & toxicology ; Dr k.s narayan reddy ; 28th edition ; Pg.no. 125 Fine grains travel 60cm or more ,one gram of powder produces 3,000-4,500c.c of gas', 'role': 'assistant'}]