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': 'Ring scotoma is a feature of – \nSelect and explain. \nA. Blue dot cataract, B. Diabetic retinopathy, C. Nuclear cataract, D. Retinitis pigmentosa', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]