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': 'Obstruction in pulmonary stenosis may occur at the following sites: \nSelect and explain. \nA. Supravalvular, B. Valvular, C. Subvalvular, D. All of the above', 'role': 'user'}, {'content': "Answer: D \nExplanation: d. All of the above(Ref: Nelson's 20/e p 2211-2217, Ghai 8/e p 420-423)Pulmonary stenosis can occur due to obstruction at supravalvular, valvular or subvalvular level.", 'role': 'assistant'}]