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: Social & Preventive Medicine
[{'content': 'Organophosphate insecticides are all except \nSelect and explain. \nA. Dieldrin, B. Fenthion, C. Diazinon, D. All', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is `a' i.e., Dieldrin", 'role': 'assistant'}]