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': 'Most characteristic finding of retinitis pigmentosa: \nSelect and explain. \nA. Ring scotoma, B. Peripheral field defect, C. Central scotoma, D. Diplopia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Ring scotoma', 'role': 'assistant'}]