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
Radiological signs of renal papillary necrosis 
Select and explain. 
A. Ring shadow, B. Egg in cup appearance, C. Increasingly dense nephrogram, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Other signs :

Lobster claw and ball on a tee.
Decreased nephrogram.
Complete sloughing of papillary tips.