This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney, Subject name: Medicine
[{'content': 'Most common cause of renal artery stenosis above 50 years of age is? \nSelect and explain. \nA. Atherosclerosis, B. FMD, C. Takayasu arteritis, D. RCC', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. (a) AtherosclerosisRef: Harrison 17/e, chapter 280, CMDT 2009, chapter 22, Brenner and rector's the kidney, 8/e, chapter 43", 'role': 'assistant'}]