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': 'In  a  normally  functioning  kidney, which part of the tubule has the lowest permeability to water during anti\xaddiuresis? \nSelect and explain. \nA. A, B. B, C. C, D. D', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The thick ascending limb is relatively impermeable to water even under conditions of maximal\xa0antidiuresis.', 'role': 'assistant'}]