This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Adverse Drug Effect, Subject name: Pharmacology
Renal papillary necrosis is caused by? 
Select and explain. 
A. NSAID, B. Cocaine, C. Heroin, D. Morphine
A: NSAID
Answer: A: NSAID 
Explanation: Ans. (a) NSAIDRef Harrisonys Internal Medicine 18/e, Table 285-3, Radiology Illustrated, Uroladiology: Uroradiology by SeungHyup Ki 2/e, p 471