## Core Concept
Color vision is facilitated by specialized pigments in the retina called **photopigments** or **visual pigments**. These pigments are sensitive to different wavelengths of light, allowing us to perceive a range of colors. The primary photopigments responsible for color vision are rhodopsin (sensitive to low light levels, not colors) and the cone cell pigments.

## Why the Correct Answer is Right
The correct answer, **Rhodopsin**, is the pigment primarily responsible for vision at low light levels (scotopic vision) and is not involved in color vision. Rhodopsin is sensitive to light in the blue-violet end of the spectrum but does not mediate color vision. The pigments responsible for color vision are:
- **Long-wavelength cones** (L-cones) sensitive to red light (approximately 600-700 nm)
- **Medium-wavelength cones** (M-cones) sensitive to green light (approximately 500-600 nm)
- **Short-wavelength cones** (S-cones) sensitive to blue light (approximately 400-500 nm)

## Why Each Wrong Option is Incorrect
- **Option A:** This option likely represents a cone cell pigment sensitive to long wavelengths (red light), which is involved in color vision.
- **Option B:** This could represent a cone cell pigment sensitive to medium wavelengths (green light), also crucial for color vision.
- **Option C:** This might symbolize a cone cell pigment sensitive to short wavelengths (blue light), contributing to color vision as well.

## Clinical Pearl / High-Yield Fact
A key point to remember is that defects in one or more of these color-sensitive pigments can lead to various forms of **color vision deficiency**, with red-green color blindness being the most common. This condition is usually inherited in an X-linked recessive pattern.

## Correct Answer: D. Rhodopsin.