Splitting of light into its constituent colours is known as:
A. Reflection
B. Refraction
C. Diffraction
D. Dispersion

Hint: White light dispersion is explained as the splitting of white light when it is passed through the prism into seven constituent colours. The dispersion of white light occurs because as they pass through a prism, with respect to the incident ray on the prism, the different colours of the light bend at different angles.

Complete Step-by-Step solution :
1.Let us first check what dispersion actually means. White light dispersion is described as the division of white light into seven constituent colours when it is passed through the prism.
2.On the basis of refraction and Snell's law, dispersal occurs. White light is white in appearance because it consists of the visible spectrum of every colour. Although they are much closer, the index of refraction in non-vacuous materials is specific for each colour.
3.These unique indices cause a different path to be followed by different wavelengths. On the left, white light gets into a prism, then is dispersed into a rainbow pattern in line with the wavelength.
4.As violet light has the shortest wavelength, more than the longest wavelengths of red light are slowed down.
5.The violet light is therefore bent to the greatest, and the red light is bent to the least. This separation of the seven colours of white light into its constituent seven is called light dispersion.

Hence, the correct option is D.

Note:
There is a reduction in velocity as light passes from air into the glass with a different refractive index. Red waves can travel faster because of the longer wavelengths and are the least refracted. But in the case of violet waves, the slowest can travel and the most refracted are.