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': 'A wave in ERG is due to activity of: \nSelect and explain. \nA. Pigmented epithelium, B. Rods and cones, C. Ganglion cell, D. Bipolar cell', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Rods and cones', 'role': 'assistant'}]