Answer:
Second arrow from the top.
Step-by-step explanation:
The diagram shows two dodge balls colliding. The red arrow shows the direction of force of the moving ball striking a stationary ball. We need to shows the direction of the force exerted by the stationary ball on the moving ball.
We know that every action have equal and opposite reaction. If the red arrow strikes the stationary ball, it will move in the direction of red arrow. So, the second arrow from the top will be direction of the moving ball.