This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney, Subject name: Medicine
[{'content': 'Which of the following values are suggestive of acute tubular necrosis - \nSelect and explain. \nA. Urine osmolality > 500mosmol/L H20, B. Urine sodium > 40 meq/L, C. Blood urea nitrogen/ plasma creatinine > 20:1, D. Urine creatinine/plasma creatinine > 40', 'role': 'user'}, {'content': 'Answer: B \nExplanation: In acute tubular necrosis - Urine sodium ->40meq/L Urine osmolality -<350mosmol/L BUN /plasma creatinine=10-15:1 Urine creatinine/plasma creatinine-<20 Casts-muddy brown Ref:Harrison 20th edition pg no. 291', 'role': 'assistant'}]