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': '17 year old boy presented to the outpatient with giddiness and hypeension. X-ray chast revealed anterior notching of 4th to the 8th ribs. What is the likely diagnosis? \nSelect and explain. \nA. Coarctation of aoa, B. Neurofibromatosis, C. Collagen vascular disease, D. Pneumonia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The findings here are typical of Coarctation of aoa (anterior notching). Neurofibromatosis causes posterior notching of ribs.', 'role': 'assistant'}]