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': 'All of the following are contrast radiographs except: \nSelect and explain. \nA. Arthrography, B. Tomography, C. Sialography, D. Arthrotomography', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]