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: Medicine
[{'content': "Oxygen content of the arterial blood is reduced in all except- a) Methemoglobinemia  b) Fallot's tetralogy  c) Carbon monoxide poisoning  d) Fibrosing alveolitis \nSelect and explain. \nA. ac, B. ad, C. ab, D. bd", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]