Reaction: The object exerts an equal and opposite gravitational force on Earth, pushing it upwards.
According to Newton's third law of motion, for every action, there is an equal and opposite reaction. In this case, the action is the gravitational force exerted by Earth on the object, and the reaction is the gravitational force exerted by the object on Earth.
The two forces are equal in magnitude but opposite in direction, and they act on different objects. The net force on the object is therefore the sum of the two forces, which is equal to the gravitational force exerted by Earth on the object. This net force causes the object to accelerate downward.
