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': 'Blood cholinesterase level should be estimated for three weeks, in non-fatal cases of poisoning with- \nSelect and explain. \nA. Parathion, B. Eldrine, C. Thallium sulphate, D. Arsenic oxide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Parathion is an organophosphorus compound (plasma cholinesterase activity is measured in poisoning of organophosphorus compounds).', 'role': 'assistant'}]