What does Snell's law of refraction state about the ratio of the sine of the angle of incidence to the sine of the angle of refraction for a given colour and pair of media?

The correct option is "It remains constant."

Snell's law of refraction is a fundamental law in optics that describes how light bends when it passes from one transparent medium to another. According to this law, when light of a specific colour (wavelength) travels between a given pair of media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant value.

Mathematically, this relationship is expressed as:

$$\frac{\sin \left(i\right)}{\sin \left(r\right)}=\text{constant}$$

Here, $i$ represents the angle of incidence, and $r$ represents the angle of refraction. This constant ratio is also known as the refractive index of the second medium with respect to the first medium. Because this ratio does not change for a given colour of light and a specific pair of media, the value remains constant regardless of changes to the individual angles themselves.