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': 'Radiological signs of renal papillary necrosis \nSelect and explain. \nA. Ring shadow, B. Egg in cup appearance, C. Increasingly dense nephrogram, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Other signs :\n\nLobster claw and ball on a tee.\nDecreased nephrogram.\nComplete sloughing of papillary tips.', 'role': 'assistant'}]