How does the density of the earth’s core compare to the other layers of the earth?
a) the core is the densest layer.
b) the core is the least dense layer.
c) the core is only less dense than the crust.
d) the core is only less dense than the mantle.

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.

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.