Answer:
A. how old the star is
Explanation:
The brightness of a star can be determined by what we call an Apparent magnitude. Factors that affect the brightness of a star are:
a. How far away the star is
b. The size of the star or how big a star is
c. How hot the star is.
The brightness of a star or its Apparent magnitude as seen from the Earth can be measured or determined by using a scale from -26.8 to +29.
