The law of inertia states that

a. the distance an object travels when set in motion is proportional to the force causing the movement.
b. a body at rest or in linear motion tends to stay at rest or in motion unless acted upon by an outside force.
c. a body at rest or in linear motion tends to stay at rest or in motion unless acted upon by an internal compressive force.
d. for every action there is an opposite and equal reaction.

b