What does mass measure in relation to an object?

Mass measures the amount of matter contained in an object, which is directly related to its inertia. Inertia is the tendency of an object to resist changes to its state of motion; the more mass an object has, the greater its inertia. This means that an object with greater mass will require more force to change its velocity compared to an object with less mass.

Understanding mass in this way is crucial for various principles in physics, such as Newton's laws of motion, which describe how forces interact with objects in motion. Mass is a fundamental property of matter that does not change regardless of the object's location in the universe, unlike weight, which can change due to the gravitational pull exerted on the object.

This clarification highlights the significance of mass in both theoretical and practical contexts within physical science, making it a foundational element in understanding physical phenomena. Other choices might reference related concepts, but they do not accurately encapsulate the definition of mass as thoroughly as the correct answer does.