**Core Concept**
Colour vision is a complex physiological process that involves the perception of different wavelengths of light by specialized cells in the retina. The human visual system contains two types of cones that are sensitive to different parts of the visual spectrum, allowing us to perceive a wide range of colours.

**Why the Correct Answer is Right**
Colour vision involves the activation of two types of cone cells: long-wavelength cones (L-cones) sensitive to red light, medium-wavelength cones (M-cones) sensitive to green light, and short-wavelength cones (S-cones) sensitive to blue light. The signals from these cones are then processed by opponent colour cells, which compare the activity of L-cones to M-cones and S-cones to each other. This processing allows us to perceive colours as a result of the balance between the activation of these colour-sensitive cells. The opponent colour cells are responsible for the perception of red-green and yellow-blue colours.

**Why Each Wrong Option is Incorrect**
**Option A:** Independent of wavelength of light - Colour vision is indeed dependent on the wavelength of light, as different wavelengths stimulate different types of cone cells.

**Option B:** Depends on intensity discrimination - While intensity discrimination is an important aspect of visual perception, it is not the primary mechanism underlying colour vision.

**Option D:** Minimum at fixation point - Colour vision is actually sharpest at the fixation point, as the fovea contains a high concentration of cone cells.

**Clinical Pearl / High-Yield Fact**
It's worth noting that colour vision deficiency, also known as colour blindness, is a common congenital condition that affects approximately 8% of males and 0.5% of females. This is often due to mutations in the genes encoding the L-cones or M-cones.

**✓ Correct Answer: C. Involves opponent colour cells**