The correct statement about mass is:
Mass is the measure of the amount of matter in an object.
The other statements are incorrect for the following reasons:
- Mass is not a force; it is a property of an object that gives it inertia and is related to the gravitational force it can exert or experience.
- The mass of an object is not variable; it remains constant regardless of location or environment.
- Mass is measured in kilograms (kg), not in Newtons (N), which are units of force.