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': 'An unknown patients presents with his pyrexia, constricted pupils, hypotesion, cyanosis and stupor progressing to coma. Poisoning is due to: \nSelect and explain. \nA. Phenobarbitone, B. Cannabis, C. Dhatura, D. Diphenhydramine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Phenobarbitone Among the given four options, only Phenobarbitone (Barbiturate)Q can cause constricted pupils.', 'role': 'assistant'}]