You are presented with the question "What causes objects to be pulled down on a celestial body?" and the following answer choices: 
- power
 - friction
 - black hole
 - wind
 - gravity
 - orbit
 - earth
 - eclipse

Now knowing that gravity causes objects that have mass to be pulled down on a planet and astronomy is the scientific study of the stars, planets and the other celestial bodies, choose the best answer.


 

     gravity    