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
Hypoxemia seen in: 
Select and explain. 
A. Hypoventilation, B. Myasthenia gravis, C. Pulmonary emboli, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Answer is D (All of the above): The four basic mechanisms of hypoxemia are a decrease in inspired P02 (Decreased Fi02), hypoventilation (as in Myaesthenia gravis), VQ mismatch (as in pulmonary emboli) and shunting.