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: Radiology
'String of beads' or sausage appearance of the renal aery is due to: 
Select and explain. 
A. Fibromuscular dysplasia, B. Subadventitial fibroplasia, C. Medial fibroplasia with aneurysms, D. Outercoat fibroplasia with aneurysms
A: Fibromuscular dysplasia
Answer: A: Fibromuscular dysplasia 
Explanation: Fibromuscular dysplasia