If the mass of an asteroid caused the gravitational force exerted by that asteroid, then what causes the gravitational force exerted by an asteroid?

Answer choices:
- a tree falling
 - flow of electrons
 - the shape of the asteroid
 - kinetic energy
 - solid, liquid, gas
 - the mass of the asteroid
 - the sound of the asteroid
 - the color of the asteroid

 

      the mass of the asteroid    