This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pediatrics
[{'content': 'Most commonly, ductus aeriosus is \nSelect and explain. \nA. Just proximal to the left common carotid, B. Just distal to the left subclan, C. Just distal to the left common carotid, D. Just proximal to the left subclan', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Most commonly, the ductus aeriosus is just distal to the subclan, and the ductus enters the pulmonary aery at its bifurcation. Ref: Nelson textbook of pediatrics 21st edition Pgno: 2344', 'role': 'assistant'}]