Why does the Earth exert a gravitational force on objects on its surface? A. It has an atmosphere,
B. It has mass
C. It has a magnetic field.
D. It is so dense.

B. It has mass

Explanation:

The Newtons Universal gravitacion law is : F = G.  , where F is the force exerted , m1 and m2 are the earth's mass and the object's mass, d is the distance and G the gravitacional constant. Comparing to the options we can say that the Earth exerts a gravitational force on objects on its surface because of its mass.

im srry but ur wrong the answer is d a smooth rock, some red dirt, and an empty bird's nest.