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': 'The refractive power of an emmetropic eye is about: \nSelect and explain. \nA. +50D, B. +55D, C. +60D, D. +65D', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. +60D', 'role': 'assistant'}]