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': 'Isotonic urine is formed at the level of \nSelect and explain. \nA. PCT, B. DCT, C. Ascending loop of henle, D. Descending loop of henle', 'role': 'user'}, {'content': 'Answer: B \nExplanation: PCT\xa0⇒ Isotonic urine\nDecending loop of hanle\xa0⇒ Hypertonic urine\nDCT\xa0⇒ Hypotonic urine.', 'role': 'assistant'}]