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': 'Commonest site of esophagus carcinoma is - \nSelect and explain. \nA. Upper 2/3, B. Middle 1/3, C. Lower 1/3, D. Crico-esophageal junction', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is ' b ' i.e. Middle 113", 'role': 'assistant'}]