In this scenario, when the moving soccer ball strikes the stationary soccer ball, the stationary ball will start moving in the same direction as the initially moving ball. According to the principle of conservation of momentum, the stationary ball will gain some momentum while the moving ball will slow down slightly. However, the directional movement will be the same (downfield).
Therefore, the correct response is:
The stationary soccer ball will begin moving downfield and the ball that struck it will slow down.