Which of the following accurately describes inertia?

Inertia is fundamentally defined as an object's resistance to any change in its state of motion, which means that it remains at rest or in uniform motion in a straight line unless acted upon by a net external force. This principle is integral to Newton's first law of motion, often referred to as the law of inertia, which highlights that the more mass an object has, the greater its inertia.

When we consider the options given, the second choice succinctly encapsulates the essence of inertia. It reflects how an object's mass contributes to its tendency to maintain its current state, whether that is at rest or moving uniformly.

In contrast, the other choices do not accurately convey the concept of inertia. For instance, the first option talks about a force, which is a different aspect of motion governed by Newton's second law; the third option refers specifically to free-fall dynamics, not inertia; and the last one discusses energy related to acceleration, which is unrelated to the intrinsic property of inertia itself. Thus, the answer that best describes inertia is the one emphasizing its role as a resistance to change in motion.