What is a scientific law that describes the motion of objects?

The correct choice is rooted in Newton's First Law of Motion, often referred to as the Law of Inertia. This law essentially states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. This principle highlights the inherent tendency of objects to resist changes to their state of motion, emphasizing the role of external influences in altering their trajectory or velocity.

This law is fundamental in understanding the behavior of objects in motion or at rest and forms the basis for further exploration of dynamics in physics. The other options presented offer variations that do not accurately encapsulate this law's essence, focusing instead on either incomplete descriptions of motion or principles that relate to different concepts in physics.