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
[{'content': 'Which of the following represents the best method in diagnosing medullary cystic disease of the kidney? \nSelect and explain. \nA. Ultrasound, B. Nuclear scan, C. Urography, D. Biopsy', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Kidney biopsy is the gold standard for diagnosis of renal diseases. Kidney biopsy of the coex in medullary cystic disease shows secondary glomerulosclerosis. Ref: Genetic Diseases of the Kidney By Richard P. Lifton, Page 456 ; Radiological Imaging of the Kidney By Emilio Quaia, Pages 299-300', 'role': 'assistant'}]