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: Surgery
[{'content': 'The narrowest part of the ureter is at the \nSelect and explain. \nA. Uretero-pelvic junction, B. Iliac vessel crossing, C. Pelvic ureter, D. Uretero-vesical junction', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]