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': 'IOC for pyonephrosis \nSelect and explain. \nA. USG, B. CECT, C. IVP, D. MRI', 'role': 'user'}, {'content': 'Answer: A \nExplanation: IOC\xa0for pyonephrosis\xa0- USG.', 'role': 'assistant'}]