Answer:
Cyclones and ocean currents transport heat towards the poles
Explanation:
The reason why the tropics is not getting hotter and the poles not getting colder is due to the activities of cyclones and ocean currents which transport heats towards the poles thus enabling the temperatures at the tropics and the poles to remain fairly constant.
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
<span>2) Gravity caused more-dense material to move toward the center of each planet.</span>
In order for the Earth to get larger, more mass would have to be added. Since no new mass is added in the process, It's size doesn't increase.