Final answer:
The car's displacement after traveling 40 km east and 20 km west is 20 km east, which is the net movement taking into account both distance and direction.
Step-by-step explanation:
The question asks for the displacement of a car after it travels 40 km east and then 20 km west. Displacement is a vector quantity that represents the shortest distance from the initial to the final position of an object, along with the direction of that straight line. In this scenario, the car first moves 40 km east and then moves 20 km west, resulting in a net motion of 20 km east (40 km - 20 km).
Therefore, the car's displacement is 20 km east, which is option A) 20 km east. This is because displacement considers both distance and direction and, in this case, the car ends up 20 km east from its original starting point.