A. The core is the densest layer
The Earth's core is far denser than any of the Earth's other layers. The high density is due to the immense pressure being exerted at the center of the Earth. Moreover, the Earth's center is the point where the Earth's gravity can be said to act, which means the gravitational force from the Earth is also the greatest there. The core is also composed of heavy metallic elements such as nickel, adding to its density.
