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
[{'content': 'Radiological Contrast to be preferred for demonstrating TO fistula \nSelect and explain. \nA. High osmolar iodine contrast, B. Low osmolar iodine contrast, C. Gadolinium-DTPA, D. Thick barium sulphate suspension', 'role': 'user'}, {'content': 'Answer: B \nExplanation: .', 'role': 'assistant'}]