Given,
The applied force, F=800 N
The friction, f=750 N
Friction is a force that opposes the motion of an object. Thus the net force will be equal to the difference between the applied force and the friction. As the applied force is greater than the frictional force, the net force will be in the same direction as the applied force, that is to the right.
Thus the net force is given by,
On substituting the known values,
Therefore the net force on the object is 50 N to the right. Thus, the correct answer is option 4.