What is an absorption spectrum?

A. The colors absorbed when an element gains energy

B. The energy released when an element loses energy

C. The energy released in a chemical reaction

D. The frequencies that pass through an element

Answer: option A. the colors absorbed when an element gains energy.

Justification:

The electromagnetic waves, visible light included, consists of a gamma of waves with different frequencies and wavelengths.

The visible light can be decomposed in a set of series of lines of light with different frequencies and that decomposition is what a spectrum of light is. Each series correspond to a color.

The atoms can absorb and emit photons. That is, atoms can absorb and release energy.

When the atom abosorbs a photon an electron gets excited (the electron gains energy).

The light absorbed, then, corresponds to color absortion, and the spectrum of absortion is the colors absorbed by the atom when its electrons gain energy by the absortion of photons (light).