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': 'Middle age patient presents with dysphagia for liquids. The barium esophagogram of the patient is shown below. The diagnosis is: \nSelect and explain. \nA. DES, B. Achalasia, C. NCE, D. Cancer', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) AchalasiaRef: Sabistons Textbook of surgery, 20th Edition, Page 1015* Image shows bird-beak appearance of achalasia cardia', 'role': 'assistant'}]