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: Radiology
[{'content': 'Rat tail appearance in contrast radiography is seen in? \nSelect and explain. \nA. Achalasia cardia, B. Carcinoma esophagus, C. Cork screw esophagus, D. Diffuse esophageal spasms', 'role': 'user'}, {'content': "Answer: B \nExplanation: Carcinoma esophagus REF: sabiston's 18' edition chapter 41 See table in the previous question", 'role': 'assistant'}]