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': 'An important non-respiratory function of lungs \nSelect and explain. \nA. Anion balance, B. Sodium balance, C. Potassium balance, D. Calcium balance', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Extracellular ACE on the surface endothelial cells in pulmonary circulation activates Angiotensin I to Angiotensin II.\nIt also directly affects sodium balance through epithelial sodium channels.', 'role': 'assistant'}]