The argument that best supports the student's claim is:
If the distance between two objects increases, the gravitational force between the objects will decrease.
This statement aligns with Newton's law of universal gravitation, which states that the gravitational force is inversely proportional to the square of the distance between the centers of the two masses. Therefore, as the distance increases, the gravitational force decreases, supporting the assertion that the gravitational force depends on both mass and distance.