This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oesophagus, Subject name: Surgery
[{'content': 'Maximum dilatation of esophagus occurs in: \nSelect and explain. \nA. Carcinoma at gastro esophageal junction, B. Achalasia cardia, C. Stricture of lower end, D. CRUST syndrome', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans: b (Achalasia cardia)Ref: Bailey & Love, 24,hed, p. 1017 & 23rd ed, p. 882', 'role': 'assistant'}]