In moonlight we cannot see the colours, because

Options

A. Cones and rods are equally functional
B. Only cones are functional
C. Only rods are functional
D. Depolarisation at cone cells

Answer

**Step-by-Step Solution:**

1. **Understanding Vision Mechanism:**
- The human eye has two types of photoreceptor cells: rods and cones.
- Rods are responsible for vision in low light conditions and do not detect color.
- Cones are responsible for color vision and function best in bright light.

2. **Conditions of Moonlight:**
- Moonlight is a form of dim light, which means the intensity of light is low.
- Under low light conditions, the cones (which detect color) become less active or inactive.

3. **Functional State of Photoreceptors:**
- In dim light, such as moonlight, the rods become the primary functional photoreceptors.
- Since rods do not detect color, our ability to perceive colors diminishes significantly.

4. **Conclusion:**
- Therefore, in moonlight, we cannot see colors because only the rods are functional while the cones are inactive.

5. **Correct Answer:**
- The correct option is: "only rods are functional."

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