Net force is the vector sum of the forces.
Answer: Option D
Step-by-step explanation:
The net force can be referred as the sum total of all the forces exerted up on a body. The word net refers to the total, hence net force refers to the total force which exerted upon the object.
A force is related as the displacement experienced by an object due to external factors or interaction acting up on the object. Option A,B and C are irrelevant as they are separate forces exerted up on the object.