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
Among the causes of rib notching are: 
Select and explain. 
A. Coarctation of aoa, B. Congenital interruption of aoa, C. Chronic superior venacava obstruction, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Ans. All of the above