What elements are stars mostly made of? how do we know this?

Mostly made up of Hydrogen and Helium. Spectral analysis of the star light is one of the techniques used to identify the elements.

Explanation:

Stars are made up of lighter elements like hydrogen and helium. The light and heat given out by the stars is due to the thermonuclear reactions that involve the proton proton cycle. Hydrogen fusion reactions forming helium , accompanied by the release of energy happen as a cycle in the core of the star giving it the immense heat , light and temperature.Heavier elements like Carbon, Nitrogen , Oxygen , and iron are also found in some stars.

The elements found in the star are detected using many techniques.. Spectral analysis of the star light is one of the methods that can be used to identify the elements found in the stars.  

are there options? cause you ain’t. real specific

the answer is a. the yacht traveled from the dock north to the 200-meter marker in the bay in less than 5 minutes, giving the passengers several more hours to fish.

im doing peak rn so sry if its wrong