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: Gynaecology & Obstetrics
[{'content': 'Which of the following tubal obstruction locations is least amenable to surgical repair? \nSelect and explain. \nA. Fimbrial, B. Interstitial, C. Ampullary, D. Isthmic', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Proximal obstruction of Fallopian tube especially\xa0Interstitial part is very prone to repeated obstruction post-operatively. So it cannot be treated with cannulation.', 'role': 'assistant'}]