Why does the size of a white dwarf affect its visual luminosity?

A typical white dwarf has a carbon and oxygen mass similar to the Sun, but is much smaller in size (similar to the Earth). It is much hotter (25,000 K), but because of its small size its luminosity is low. ... Some very nearby white dwarf stars can be observed directly through telescopes, though they are extremely faint.

Explanation:

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )

massxgravity x heght=weightxheight= pe

4900=490xh

h=10