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
Superior rib notching is/are caused by – a) Hyperparathyroidismb) Poliomyelitisc) Blalock tausing shuntd) Marfan syndromee) Coarctation of aorta 
Select and explain. 
A. acd, B. bcd, C. abc, D. abd
D: abd
Answer: D: abd 
Explanation: Hyperparathyroidism, poliomyelitis and Marfan's syndrome cause notching of superior surface of rib.