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: None', 'role': 'assistant'}]