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
[{'content': 'Which of the following causes rib-notching on the chest radiography? \nSelect and explain. \nA. Bidirectional Clem shunt, B. Modified Blalock-Taussing shunt, C. IVC occlusion, D. Coarctation of aoa', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Coarctation of aoa', 'role': 'assistant'}]