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': 'Radial keratotomy is used as a treatment modality for – \nSelect and explain. \nA. Small degree in myopia, B. Progressive non healing ulcer, C. High astigmatism, D. High hypermetropia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Radial keratotomy is used for low to moderate myopia (-2 to -6D).', 'role': 'assistant'}]