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: Medicine
[{'content': "Crack-Nut oesophagus seen in - \nSelect and explain. \nA. Carcinoma oesophagus, B. Cardiospam, C. Achalasia cardia, D. Barrett's oesophagus", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]