You are presented with the quiz "what part of a planet causes the pull of gravity on that planet?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "the mass of a planet causes the pull of gravity on that planet" and "mass, the amount of matter in an object, is measured in grams". 

So, what's the best answer to the question?


 

     amount of matter      