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': 'Piles occurs at- \nSelect and explain. \nA. Superior rectal vein, B. Inferior rectal vein, C. Superior Hemorrhoidal aery, D. None', 'role': 'user'}, {'content': "Answer: A \nExplanation: Answer- A. Superior rectal veinInternal hemorrhoids in association with superior rectal vessels are located at 3, 7 and 11 O'clock positions corresponding to left, right posterior and right anterior branches of these vessels.", 'role': 'assistant'}]