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
The accurate diagnostic aid in renal artery stenosis is - 
Select and explain. 
A. Selective renal angiography, B. Ultrasound, C. CT scan, D. IVU
A: Selective renal angiography
Answer: A: Selective renal angiography 
Explanation: None