What are sky maps? how are they made

ANSWER:

A sky map is a map that shows the various stars in the sky in a specific area or location.

EXPLANATION:

Sky maps tell which star is which in the sky. These maps show the stars along with other bodies in the sky and also show the parent stars from which stars take their light and show their presence. Sky maps are created by astronomers by using telescopes to watch the stars and using a method of conical angular rotation to map the night sky.

It’s either c or d as the answer.

Themes; subfields is the answer