This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetics And Genetic Disorders, Subject name: Pediatrics
[{'content': 'Most common heart lesion in down syndrome: \nSelect and explain. \nA. Endocardial cushion defect, B. ASD with ostium secundum, C. VSD, D. Coarctation of aorta', 'role': 'user'}, {'content': "Answer: A \nExplanation: a. Endocardial cushion defect(Ref: Nelson's 20/e p 610-614)Most common cardiac defect in Down syndrome is Endocardial cushion defect or Atrioventricular septal defect", 'role': 'assistant'}]