You are presented with the question "What causes the gravitational force exerted by an asteroid?" and the following 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

Now knowing that the mass of an object causes the gravitational force exerted by that object and an asteroid is a rock-like object with an irregular shape, choose the best answer.


 

      the mass of the asteroid   