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: Orthopaedics
[{'content': 'Marfan syndrome is due to \nSelect and explain. \nA. Fibrillin 1 defect, B. Fibrillin 2 defect, C. Fibrillin 3 defect, D. Fibrillin 4 defect', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]