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: Medicine
[{'content': 'Most common cardiovascular abnormality in Down syndrome \nSelect and explain. \nA. Endocardial cushion defects, B. VSD, C. PDA, D. Pulmonary hypertension', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Endocardial cushion defects - 43%\nVSD - 32%', 'role': 'assistant'}]