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': 'Cupping of optic disc is seen in: March 2004 \nSelect and explain. \nA. Trachoma, B. Open angle glaucoma, C. Retinitis pigmentosa, D. Retinoblastoma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B i.e. Open angle glaucoma', 'role': 'assistant'}]