This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S., Subject name: Medicine
[{'content': "What is the diagnosis in this 31-year-old woman with gradual bilateral vision loss? \nSelect and explain. \nA. Glaucoma, B. Graves' ophthalmopathy, C. Marfan's syndrome, D. Retinitis pigmentosa", 'role': 'user'}, {'content': "Answer: C \nExplanation: Answer C. Marfan's syndromeThe imaging shows posterior dislocation of the lens in both eyes. The most common cause of bilateral ectopia lentis is Marfan's syndrome, the diagnosis in this case.", 'role': 'assistant'}]