This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Surgery
[{'content': 'This is a barium swallow showing \nSelect and explain. \nA. Carcinoma esophagus, B. Achalasia cardia, C. Nut cracker esophagus, D. Oesophageal stricture', 'role': 'user'}, {'content': 'Answer: A \nExplanation: This is an image of the distal esophagus from a barium swallow demonstrating an irregular, somewhat nodular filling defect probably due to carcinoma oesophagus', 'role': 'assistant'}]