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': 'Early stage of carcinoma esophagus is diagnosed by ? \nSelect and explain. \nA. Barium meal, B. Trans oesophageal USG, C. MRI, D. Endoscopy', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e. Endoscopy", 'role': 'assistant'}]