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
Radiological Contrast to be preferred for demonstrating TO fistula 
Select and explain. 
A. High osmolar iodine contrast, B. Low osmolar iodine contrast, C. Gadolinium-DTPA, D. Thick barium sulphate suspension
B: Low osmolar iodine contrast
Answer: B: Low osmolar iodine contrast 
Explanation: .