A bowling ball collides with a pin and pushes the pin toward the right. Which describes the reaction force?

the reaction force is to the left and of the same magnitude

Explanation:

To analyze this collision we see that when the bowling ball collides with the pin it exerts a force on it and by the law of action and reaction the pin exerts a force of equal magnitude and opposite direction on the ball.

Due to the high difference in mass, the speed and direction of the bowling ball is little altered, instead the speed and direction of the pin change significantly.

In summary the reaction force is to the left and of the same magnitude