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': 'False about Coarctation of Aorta \nSelect and explain. \nA. Double bulge sign is seen, B. Double aortic knuckle, C. Rib notching is seen in 1-8 ribs, D. Rib notching increases with age', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Rib notching is absent in 1st and 2nd ribs because first and second intercostal arteries do not take part in Collateral Circulation.', 'role': 'assistant'}]