What does Newton's first law of motion state?

Newton's first law of motion, often referred to as the law of inertia, emphasizes the concept that an object will remain in its current state of motion—whether at rest or in uniform motion in a straight line—unless acted upon by an unbalanced external force. This principle illustrates the natural tendency of objects to resist changes in their state of motion, which is integral to understanding both classical mechanics and the behavior of objects in various situations.

According to this law, if there are no net forces acting on an object, it will not change its velocity. For instance, a book lying on a table will remain at rest until someone applies a force to move it. Similarly, a ball rolling on a smooth surface will continue to roll at a constant speed and in a straight line until a force—like friction or an obstacle—interferes.

The other options present misunderstandings of this law or apply incorrect concepts. Hence, the correct interpretation aligns directly with the principle established by Newton regarding inertia and the conditions necessary for an object to change its state of motion.