Answer: The correct answer is option d.
Explanation:
Apparent brightness depends on two factors: Luminosity and location of the observer.
Luminosity is defined as the amount of energy that a star emits from its surface. It depends on the Temperature and radius (size) of the star.
\(L\propto R^2T^4\)
And, here observer is Earth, so the apparent brightness will depend on the distance of star from Earth.
Hence, the correct option is Option d.
