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: Medicine
[{'content': 'Reversal of shunt is not possible in the natural history of \nSelect and explain. \nA. ASD, B. TOF, C. VSD, D. PDA', 'role': 'user'}, {'content': "Answer: B \nExplanation: Eisenmenger's syndrome or reversal of shunt is seen in the ventricular septal defect, atrial septal defect, or less commonly, patent ductus aeriosus. ref - Harrisons internal medicine 20e pg 393,1838", 'role': 'assistant'}]