Answer: The correct answer is A.
Step-by-step explanation:
Matter can absorb or emit the light. It does not matter what is the source of light. It may be the surface of sun or star.
Atmosphere absorbs the part of white light which is emitted from star. It produces a color spectrum marked by the dark lines. These dark lines are absorption lines. These lines show the characteristics of the elements present in the gas.
The spectrum of star gives the information about the chemical composition of its atmosphere.
Therefore, Absorption of light in star's atmosphere is the scientific phenomenon which helps scientists to determine the chemical composition of some star.