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': 'Not a stimulus for pulmonary vasoconstriction: \nSelect and explain. \nA. Hypoxemia, B. Hypercapnia, C. PGI2, D. Thromboxane', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. PGI2The unique feature of pulmonary vasculature is that the hypoxia tends to produce Vasconstriction (where as in other system it produces Vasodilation)', 'role': 'assistant'}]