Q:Fact 1: The mass of a planet causes the pull of gravity on that planet. Fact 2: Mass, the amount of matter in an object, is measured in grams. Given the two facts above, answer the question "what part of a planet causes the pull of gravity on that planet?" with the following options: - solid, liquid, gas - layers of fat - barrel-shaped - our star - amount of matter - an external framework - hydrogen and oxygen - It expands
A:
amount of matter