Newton's third law states that when an object exerts a force on another object, the second object exerts an equal but opposite force on the first object. Which of the following shows an example of this?
a. A bumper car crashes into a wall, causing it to bounce backwards.
b. A woman presses on both sides of a box with equal force.
c. A moving cart becomes more difficult to stop as more mass is added to it.
d. A parked car sits in the same place for two weeks until another car runs into the back of it.