Here's why:
* Luminosity: Luminosity is the total amount of light energy a star emits per second. It depends on both the star's temperature and its surface area.
* Size: A larger star has a greater surface area.
* Temperature: A hotter star emits more light per unit area.
Since stars A and B have the same luminosity, the larger surface area of star A must be compensated for by a lower temperature. In other words, star A is cooler and emits less light per unit area, while star B is hotter and emits more light per unit area to achieve the same overall luminosity.
