This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidneys and Body Fluids, Subject name: Physiology
[{'content': 'Which part of the nephron is impermeable to water \nSelect and explain. \nA. A, B. B, C. C, D. D', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) C(Ref: Guyton and Hall Physiology Review, 3rd ed/p.83)Point C is the thick ascending loop of HenleIt is impermeable to water', 'role': 'assistant'}]