Question

Which statement best explains why Earth and

the other planets of our solar system became
layered as they were being formed?
(1) Gravity caused less-dense material to move toward the center of each planet.
(2) Gravity caused more-dense material to move toward the center of each planet.
(3) Materials that cooled quickly stayed at the surface of each planet.
(4) Materials that cooled slowly stayed at the surface of each planet.

Answer 1

The main mechanism through which the layering happened is gravity: it pulled the heavier, denser material to the center, leaving the less dense material on the surface.

The material that was on the outside cooled quicker, but this was the result, not the cause.

The answer is
2) Gravity caused more-dense material to move toward the center of each planet.