Final answer:
Most stars produce an absorption spectrum, which shows dark lines on a continuous spectrum, corresponding to specific wavelengths absorbed by atoms in a gas cloud.
Step-by-step explanation:
Stars can produce all three kinds of spectra, but most produce an absorption spectrum. The absorption spectrum consists of a series or pattern of dark lines, representing specific wavelengths that are missing, which are superimposed upon the continuous spectrum of a light source. This occurs when light from a star passes through a cooler gas cloud before reaching the observer.
The atoms in the gas cloud absorb light at specific wavelengths which corresponds to the energy needed to excite electrons in the atoms to a higher energy level. When we observe these missing wavelengths against the continuous spectrum, we see the characteristic dark lines of an absorption spectrum.