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': 'In which of the following a reduction in arterial oxygen tension occurs? \nSelect and explain. \nA. Anaemia, B. CO poisoning, C. Moderate exercise, D. Hypoventilation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Hypoventilation leads to hypoxic hypoxia where both arterial oxygen content and PO2 is low.', 'role': 'assistant'}]