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 is seen in: \nSelect and explain. \nA. Achalasia cardia, B. Reflux esophagitis, C. Carcinoma oesophagus, D. Hiatus hernia', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Carcinoma oesophagus', 'role': 'assistant'}]