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
Which among the following is characteristic of a/c glomerulonephritis: Need to change the format? 
Select and explain. 
A. Muddy brown Cast, B. FeNa < 1%, C. Haematuria Proteinuria, D. WBC
B: FeNa < 1%
Answer: B: FeNa < 1% 
Explanation: Ref: Harrison's 18/e p2300