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: Physiology
[{'content': 'Least A-V O2 difference is seen in ? \nSelect and explain. \nA. Hypoxic hypoxia, B. Anemic hypoxia, C. Stagnant hypoxia, D. Cyanide poisoning', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Cyanide poisoning", 'role': 'assistant'}]