Fact 1: The mass of an object causes the gravitational force exerted by that object.

Fact 2: Gravitation is a universal force of attraction acting between all matter.

Given the two facts above, answer the question "What causes the amount of attraction exerted by an object?" with the following options: 
- mass
 - motion
 - motors
 - heat
 - energy
 - wind
 - fibers
 - fields


 

 mass        