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': 'Most common motility disorder leading to dysphagia: \nSelect and explain. \nA. Nut cracker esophagus, B. Esophageal web, C. Diffuse esophageal spasm, D. Achalasia cardia', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. (d) Achalasia cardiaRef: Sabiston 20th Edition, Pagesl015-1018* Most common motility disorder -- Achalasia* Most common hypermotility disorder: Nut cracker esophagus', 'role': 'assistant'}]