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': 'Diameter of an adult crystalline lens is: \nSelect and explain. \nA. 5-6 mm, B. 7-8 mm, C. 9-10 mm, D. 11-12 mm', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. 11-12 mm', 'role': 'assistant'}]