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': 'Maximum dilatation of esophagus occurs in? \nSelect and explain. \nA. Carcinoma at gastro esophageal junction, B. Achalasia cardia, C. Stricture at lower end, D. CREST syndrome', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e. Achalasia cardia", 'role': 'assistant'}]