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
What is the most common cause of chronic renal failure? 
Select and explain. 
A. Glomerulonephritis (acute to chronic), B. Chronic pyelonephritis, C. Diabetes mellitus, D. Hypeensive renal disease
C: Diabetes mellitus
Answer: C: Diabetes mellitus 
Explanation: The most common cause of chronic renal failure is diabetes mellitus, not glomerulonephritis. Foy percent of patients with Type I diabetes mellitus eventually develop diabetic nephropathy chronic renal failure. Twenty percent of patients with Type II diabetes mellitus develop diabetic nephropathy and subsequent chronic renal failure. Ref: Obrador G.T. (2009). Chapter 17. Chronic Renal Failure & the Uremic Syndrome. In E.V. Lerma, J.S. Berns, A.R. Nissenson (Eds), CURRENT Diagnosis & Treatment: Nephrology & Hypeension.