9.
the gravitational field strength is a property of the within earth's gravitational field.

a. motion
b. velocity
c. mass
d. location

D. location

Explanation:

The gravitational field strength of Earth is determined by the virtue of the location within the Earth's gravitational field.

That's why all objects regardless of their mass, shape, and size free fall towards the Earth with an acceleration equal to the acceleration at that location in the absence of air resistance.

According to the gravitational force between two bodies, the force experienced by one body due to the other is independent of its own mass.

The gravitational force is given by equation

                                  F =  GMm/r²

If F is the force acting on the smaller body of mass 'm', then

                                 F = ma

Therefore, the equation becomes,

                                ma = GMm/r²

                                   a = GM/r²

The value of 'a' changes with respect to the value of 'r' such that if 'r' is the radius of the Earth, then the acceleration at a height 'h' from Earth surface is given by

                                 a = GM/(r+h)²

Here it is clear that the acceleration at any point is only the inherent property of the Earth itself.

The gravitational field strength of Earth is determined by the virtue of the location within the Earth's gravitational field.