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: Ophthalmology
[{'content': "Dislocation of lens is seen in all the following conditions except: \nSelect and explain. \nA. Congenital rubella, B. Marchesani's syndrome, C. Marfan syndrome, D. Homocystimuria", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Congenital rubella', 'role': 'assistant'}]