Why is NSAIDs use a relative contraindication in patients with chronic renal failure?

• A. direct toxic effects on proximal tubule
• B. direct toxic effects on collecting ducts
• C. indirect toxic effects on loop of Henle
• D. inhibition of prostaglandin synthesis which is an important regulator of renal blood flow in arterioles
• E. inhibition of prostaglandin synthesis which is an important regulator of renal blood flow in main renal arteries