A body is subjected to a force of module F constant and parallel to the support plane; it is verified that the resulting motion is rectilinear and uniform with speed V.

From this we conclude that the friction force:

A) is orthogonal to the plane of motion

B) is equal and opposite to the force F

C) is = 0

D) is half the force F and has the same direction and sense

E) is half the force F and has the same direction and opposite sense

i thought it should be E) but the answer is B). How can the body move if the friction is equal and opposite??