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
All of the following are contrast radiographs except: 
Select and explain. 
A. Arthrography, B. Tomography, C. Sialography, D. Arthrotomography
B: Tomography
Answer: B: Tomography 
Explanation: None