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': 'All of the following are true about achalasia cardia except: March 2012 \nSelect and explain. \nA. Bird beaks appearance, B. Absent air bubble in stomach, C. Decreased lower oesophageal sphincter tone, D. Absent peristalsis in the body of oesophagus', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans: C, Decreased lower oesophageal sphincter toneAchalasia cardiaBarium radiology may show a tapering stricture in the distal oesophagus, often described as a 'bird's beak'. The gastric bubble is usually absent.The physiological abnormalities in achalsia cardia are non-relaxing LOS (lower oesophageal sphincter) and absent peristalsis in the body of the oesophagus.", 'role': 'assistant'}]