This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Ophthalmology
[{'content': 'What is the diagnosis of the following examination of the fundus? \nSelect and explain. \nA. Diabetes retinopathy, B. Optic atrophy, C. Acute glaucoma, D. Optic disc drusen', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Glaucoma results in "cupping" as the neural rim is destroyed and the central cup becomes enlarged and excavated. The cup-to-disc ratio is about 0.7/1.0 in this patient.', 'role': 'assistant'}]