Which sentence states Newton’s third law? A.
If two objects collide, each object exerts a force in the same direction as the other.
B.
If two objects collide, each object exerts a force equal to and in the opposite direction of the other.
C.
A collision between a moving object and a stationary object is elastic.
D.
A collision between a moving object and a stationary object is inelastic.
E.
If two objects collide, the moving object exerts a greater force than the stationary object.

A. If two objects collide, each object exerts a force in the same direction as the other.

Explanation:

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.