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': 'Inferior rib notching is seen in \nSelect and explain. \nA. Coarctation of aoa, B. Rickets, C. ASD, D. Multiple myeloma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Coarctation of aoa Inferior rib notching in coarctation of aoa is d/t pressure erosion of intercostal aeriesQ It usually takes several years to develop, so is unusual before 10 years of age.', 'role': 'assistant'}]