Answer: dispersion
The dispersion of light occurs when a beam of white light (which is compound of many wavelengths or "colors") is refracted (the different rays of light are diverted depending on their wavelengths) in some medium, leaving their constituent colors separated.
The best known case is when a beam of white light from the sun passes through a prism, thus obtaining rays of different colors like those of the rainbow.
This phenomenom was named by Isaac Newton in the eighteenth century, who performed the experiment explained above.
Hence, the correct option is C.