This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
[{'content': 'In acute tubular necrosis, all are true except \nSelect and explain. \nA. Specific gravity of urine < 1.020, B. Urine Osmolatlity > 500, C. Blood urea: creatinine ratio < 20, D. Urine sodium < 20mmol/l', 'role': 'user'}, {'content': "Answer: D \nExplanation: Acute tubular necrosis: - Muddy brown granular or tubular epithelial cell casts- FENa > 1%- UNa > 20 mmol/L- SG < 1.015 Ref: Harrison's 17/e p1757 table 273-2", 'role': 'assistant'}]