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': 'Incidence of primary open-angle glaucoma in population over 40 years of age is about: \nSelect and explain. \nA. 1 in 100, B. 1 in 200, C. 1 in 500, D. 1 in 1000', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. 1 in 100', 'role': 'assistant'}]