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
In electroretinogram (ERG) the b-wave represents the activity of: 
Select and explain. 
A. Rods and cones, B. Bipolar cells, C. Ganglion cells, D. All of the above
B: Bipolar cells
Answer: B: Bipolar cells 
Explanation: Ans. Bipolar cells