This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diseases of the Aorta, Subject name: Medicine
In coarctation of aorta, site of rib notching is? 
Select and explain. 
A. Superior to rib, B. Inferior to rib, C. At sternum, D. At Vertebra
B: Inferior to rib
Answer: B: Inferior to rib 
Explanation: Ans. (b) Inferior to ribCauses of inferior rib notchingCauses of superior rib notching* Arterial: aortic coarctation, aortic thrombosis, pulmonary- oligemia/AV malformation, Blalock Taussig shunt, Tetralogy of fallot, absent pulmonary artery and pulmonary stenosis.* Venous: AV Malfomations of chest wall, superior vena cava or other central venous obstruction.* Neurogenic: Intercostal neuroma, Neurofibromatosis type 1, poliomyelitis.* Osseous: Hyperparathyroidism, Thalassemia* Poliomyelitis* Osteogenesis Imperfecta* Neurofibromatosis* Marfan's Syndrome* Collagen vascular disease* Hyperparathyroidism.