This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Death and postmortem changes, Subject name: Forensic Medicine
[{'content': 'Fat mesentery is sent for investigation in which poisoning - \nSelect and explain. \nA. Carbon monoxide, B. Organophosphorus, C. Arsenic, D. Lead', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Fat mesentery is preserved in OP poisoning. Dr. Narayana Reddys Synopsis of Forensic Medicine & Toxicology 27 th edition pg. 61.', 'role': 'assistant'}]