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 is: \nSelect and explain. \nA. Anion balance, B. Sodium balance, C. Potassium balance, D. Ca2+ balance', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]