Gravity causes objects that have mass to be pulled down on a planet, and another name for Mars is the Red Planet. Given these facts, gravity causes what to be pulled down on Mars among the following options:
- space
 - living things
 - hydrogen and oxygen
 - massless objects
 - objects that have mass
 - fissures of hot, acidic water
 - nothingness
 - principals of aerodynamics


 

     objects that have mass    