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
Which of the following is not true about intrinsic renal failure in case of ischemic ATN? 
Select and explain. 
A. Specific gravity < 1.015, B. FENa < 1, C. Urine sodium > 20 mmol/L, D. Urine creatinine to plasma creatinine ratio < 20
C: Urine sodium > 20 mmol/L
Answer: C: Urine sodium > 20 mmol/L 
Explanation: Ans. c. Urine sodium > 20 mmol/L. (Ref H-18th/Table 44-2) Index Prerenal Azotemia *(lschemic ATN)Oliguric Acute Renal FailureBUN/PCr Ratio>20:110-15:1Urine sodium (UNa), mEq/L<20>40Urine osmolality, mOsm/L H2o>500<350Fractional excretion of sodium<1%>2%FENa=UN, x PCr x 100---------PNa,x UCr Urine/plasma creatinine (UCr/PCr)>40<20