If a system stores kinetic energy, which choice must be true?

1. the molecules, atoms, and/or subatomic particles must be exerting forces on each.
2. the molecules, atoms, and/or subatomic particles must be at rest.
3. the molecules, atoms, and/or subatomic particles must be within earth’s gravitational field.
4. the molecules, atoms, and/or subatomic particles must be moving.

4. The molecules, atoms, and/or subatomic particles must be moving.

Explanation:

The only answer can be considered to be true is 4.

The answer 1 refers to elastic potential energy and answer 2 refers to gravitational potential energy.

If a body to store kinetic energy then as the word 'Kinetic' suggest the object should store the energy in form of motion. So only  answer that can be considered is 4.

Option 4: The molecules, atoms, and/or subatomic particles must be moving.

Explanation: Kinetic energy is the energy related to the movement, and is described by the equation:

K = m/2*v^2

where m is the mass of the object and v is the velocity of the object.

Then, if a system is storing kinetic energy, this means that the molecules, atoms and subatomic particles must have a velocity, this means that they are moving, then the correct option is the fourth one.