Which of the following best defines inertia?

Inertia is best defined as the resistance of an object to change its state of motion. This concept, rooted in Newton's First Law of Motion, states that an object at rest will remain at rest, and an object in motion will continue moving at a constant velocity unless acted upon by a net external force. Therefore, inertia is fundamentally a property of mass that describes how much an object resists changes to its current state, whether that state is being at rest or in motion.

The other definitions do not accurately depict inertia. While the tendency of an object to accelerate involves the application of force, it does not encompass the concept of resisting changes in motion. The force exerted by gravity pertains more to gravitational interactions rather than inertia itself. Finally, the energy possessed by a moving object is defined as kinetic energy, which is a separate principle from inertia. Thus, B provides the most accurate understanding of inertia in the context of physics.