Answer:
A. Chemical composition of the star
Step-by-step explanation:
'Each element absorbs light at specific wavelengths unique to that atom. When astronomers look at an object's spectrum, they can determine its composition based on these wavelengths' - astronomy.com
'Atomic emission spectra are unique spectra of light emitted by an element when electricity is run through it or when it is viewed through a prism. Because they are unique, they can act as an element s fingerprint' - brightstorm.com