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: Medicine
Medullary cystic disease of the kidney is best diagnosed by - 
Select and explain. 
A. Ultrasound, B. Nuclear scan, C. Urography, D. Biopsy
D: Biopsy
Answer: D: Biopsy 
Explanation: None