## Core Concept
The question pertains to the physiology of the visual pathway, specifically focusing on the types of cells and their response to light. In the context of the retina and visual pathway, cells can respond to light by either depolarizing or hyperpolarizing. Purely depolarizing cells are those that depolarize in response to light.

## Why the Correct Answer is Right
The correct answer, **bipolar cells**, are indeed purely depolarizing or hyperpolarizing depending on their type, but in the context of this question, it seems to be pointing towards a specific subset. However, more accurately, **ON bipolar cells** are depolarized by light. These cells are crucial for transmitting visual information from photoreceptors to ganglion cells. They use **glutamate receptors** and the signaling pathway involves a decrease in glutamate release from photoreceptors in light, which then leads to depolarization of ON bipolar cells.

## Why Each Wrong Option is Incorrect
- **Option A:** This option seems to be missing but typically, photoreceptors (rods and cones) hyperpolarize in response to light, not depolarize.
- **Option B:** This seems to be missing but could potentially refer to certain types of retinal cells; however, without specifics, it's hard to address directly.
- **Option C:** This option seems to be missing but could refer to amacrine cells, which can have various responses and are not purely depolarizing.
- **Option D:** This option seems to be missing but could potentially refer to ganglion cells or other retinal cells; however, the question focuses on purely depolarizing cells.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **ON bipolar cells** are depolarized by light through a unique mechanism involving **mGluR6 receptors**, which are metabotropic glutamate receptors. This leads to a closure of potassium channels, causing depolarization. This is a critical aspect of visual processing and understanding the pathway of visual information.

## Correct Answer: B.