This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Surgery
[{'content': 'Ivor Lewis operation is the treatment of choice for cancer involving _____ esophagus \nSelect and explain. \nA. Middle 1/3rd, B. Lower 1/3rd, C. Upper 1/3rd, D. Entire Esophagus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: .', 'role': 'assistant'}]