What defines any action on a body that tends to change its size, shape, or state of motion?

The correct answer is force, as it is fundamentally defined as any influence that can change the motion of an object or alter its shape, size, or state. Force originates from a push or a pull applied to an object, which can lead to acceleration, deceleration, or deformation. For example, when you push a stationary object, the force you exert can set it into motion. Similarly, when force is applied to a material, it can cause the material to change shape or size, such as stretching or compressing a spring.

While work and energy relate closely to force by describing the relationship between force and movement or changes in energy levels, they do not solely define the action of influence itself. Pressure refers to the force exerted per unit area, which is a different concept focused on the distribution of force rather than the influence of force in changing motion or shape. Therefore, force stands out as the key term that encompasses any action capable of altering the state or shape of a body.