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': 'A dead body with suspected poisoning is having hypostasis of red brown or deep blue in colour. It is suggestive of poisoning due to \nSelect and explain. \nA. Nitrates, B. Carbon monoxide, C. Cyanides, D. Barbiturates', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Nitrates', 'role': 'assistant'}]