Why the vitamin-A (retinol) is essential for night vision?

Explanation

### Step-by-Step Solution:

1. **Understanding Night Vision**: Night vision refers to the ability to see in low-light conditions. This ability is primarily facilitated by specific cells in the retina known as rod cells.

2. **Role of Rod Cells**: Rod cells are photoreceptor cells in the retina that are sensitive to light. They are responsible for vision in dim light and are crucial for night vision.

3. **Presence of Rhodopsin**: Rod cells contain a light-sensitive pigment called rhodopsin. This pigment is essential for detecting light and enabling vision in dark environments.

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