The correct option is A.
In physics, inertia has to do with Newton's first law of motion which states that an object will continue in its state of rest or in motion unless it is acted upon by a force. Thus, inertia refers to the tendency of an object to continue its motion in a straight line at constant velocity. In the question given above, the car that its brake failed would have continue moving indefinitely if it did not crash into another car, that is, it will continue in its state of motion.
