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': "Adenocarcinonia in oesophagous occurs in - \nSelect and explain. \nA. Middle esophagus, B. Upper esophagus, C. Barret's ulcer, D. None of the above", 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]