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': 'Which of the following is the best-known metabolic function of the lung \nSelect and explain. \nA. Inactivation of serotonin, B. Conversion of angiotensin–I to angiotensin–II, C. Inactivation of bradykinin, D. Metabolism of basic drugs by cytochrome P–450 system', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Extracellular ACE on the surface endothelial cells in pulmonary circulation activates Angiotensin I to Angiotensin II.', 'role': 'assistant'}]