This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen and pelvis, Subject name: Anatomy
[{'content': 'The uterine pa of uterine tube opens at the superior angle of the uterine cavity by ? \nSelect and explain. \nA. Isthmus, B. ostium, C. plexus, D. Fold', 'role': 'user'}, {'content': "Answer: B \nExplanation: The uterine or intramural or interstitial pa of the tube is about 1 cm long and lies within the wall of the uterus. It opens at the superior angle of the uterine cavity by a narrow uterine ostium. This ostium Is about 1 mm in diameter. Ref : B D Chaurasia's Human Anatomy , Seventh Eedition , Volume 2 , Pg. no.,417.", 'role': 'assistant'}]