Which of the following describes inertia?
A.
Objects in motion will slow down and objects at rest will stay at rest unless the objects are acted on by an outside force.

B.
Objects in motion will stay in motion and objects at rest will begin moving unless the objects are acted on by an outside force.

C.
Objects in motion will speed up and objects at rest will stay at rest unless the objects are acted on by an outside force.

D.
Objects in motion will stay in motion and objects at rest will stay at rest unless the objects are acted on by an outside force.