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: Pediatrics
[{'content': "Which one of the following is the most common cause of cyanotic hea disease- \nSelect and explain. \nA. Dextrocardia, B. Fallot's tetralogy, C. Atrial septal defect, D. Coarctation of aoa", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Fallot's tetralogy", 'role': 'assistant'}]