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': 'X-Ray appearance of CBD stone on cholangiography is: \nSelect and explain. \nA. Meniscus appearance, B. Sudden cut off, C. Smooth tapering, D. Eccentric occlusion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Meniscus appearance', 'role': 'assistant'}]