A

The answer is spectroscopy.

Explanation:

Spectroscopy is concerned with the exploration and analysis the electromagnetic spectrum of light. The electromagnetic spectrum is the term used to describe the variety of frequencies of electromagnetic radiation.

Different wavelengths of electromagnetic waves produce various colors. Some of these colors can be seen by the human eye, and this part of the spectrum is known as the visible spectrum.

For example, the human eye sees electromagnetic waves 700–635 nm long as the color red, and the wavelength of 560–520 nm as the color green. Originally, spectroscopy studies focused on how visible light was dispersed by a prism, producing different component wavelengths on the spectrum, like in the image below.

Thus, the classification of colors by wavelengths is among the major achievements in this area.

The electromagnetic spectrum of light.
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