At the center of the Earth is the core, which has two parts. The solid, inner core of iron has a radius of about 760 miles (about 1,220 km), according to NASA. It is surrounded by a liquid, outer core composed of a nickel-iron alloy. The outer core is about 1,355 miles (2,180 km) thick.
The answer is D. Gravity.
Gravity attracts objects to the surface of the Earth. Take a falling brick, for example, the brick has more mass, therefore, there is more attraction between the brick and Gravity. The brick is a solid object and is heavier as well.
Hope this helps! :)
Does this come with choices?
Pretty sure it's gravity :)