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': 'In electroretinogram (ERG) the b-wave represents the activity of: \nSelect and explain. \nA. Rods and cones, B. Bipolar cells, C. Ganglion cells, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Bipolar cells', 'role': 'assistant'}]