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
Plasma urea / creatinine ratio of 20:1 may be seen in - 
Select and explain. 
A. Rhabdomyolysis, B. Ureteric calculi, C. Pre-renal failure, D. Chronic glomerulonephritis
C: Pre-renal failure
Answer: C: Pre-renal failure 
Explanation: None