Fact 1: Gravity causes objects that have mass to be pulled down on a planet.

Fact 2: Rocks have mass.

Given the two facts above, answer the question "What does gravity cause to be pulled down on a planet?" with the following options: 
- matter
 - heat
 - earth
 - solutes
 - oceans
 - Rocks
 - people
 - Lift


 

      Rocks   