In this scenario, when a moving soccer ball with a force of 1.2 kN collides with a stationary soccer ball, the laws of physics, particularly the principles of momentum conservation, apply.
The moving soccer ball will transfer some of its momentum to the stationary soccer ball upon impact. As a result, the stationary soccer ball will start moving in the direction that the first soccer ball was traveling (upfield). The moving soccer ball will slow down as it transfers some of its momentum to the other ball.
Therefore, the best description of the result of the collision is:
The stationary soccer ball will begin moving upfield and the ball that struck it will slow down.