The colour of the light is fixed by its

The correct answer is (c) Frequency.

The frequency of light is the number of waves that pass a given point in a given amount of time. The higher the frequency, the shorter the wavelength. Different frequencies of light correspond to different colors. Red light has the lowest frequency and longest wavelength, while violet light has the highest frequency and shortest wavelength.

The velocity of light is the speed at which light travels through a vacuum. The velocity of light is a constant, and it is not