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': 'Keratometer is used for ? \nSelect and explain. \nA. Corneal thickness, B. Corneal diameter, C. Corneal curvature, D. Distance between cornea and pupil', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Corneal curvature", 'role': 'assistant'}]