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 cardiac defect in Turner syndrome \nSelect and explain. \nA. Pretruncal coarctation of aorta, B. Bicuspid aortic valve, C. Hypoplastic left heart, D. Mitral regurgitation', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B > A', 'role': 'assistant'}]