A narrow beam of white light can be spilt up into different colours by a glass of prism. The correct explanation is that
white light is an electromagnetic wave
the prism has all colours of white light
different colors of white light travel with different speeds in glass
white light has undergone total internal reflection in the prism
The diffraction of light is the phenomenon whereby light is separated into its constituent colors by a prism because different colors of light travels at different speeds in glass.