Since there is a meeting of the cables at their midpoints, it is therefore understood that the force on them is the same but in the opposite direction, this to maintain the static balance between the two.
This can also be corroborated by applying the right hand rule for the force, at which depends of the magnetic field. The net force is zero because the cable segment to the left of the vertical cable feels an opposite force in the direction of the cable segment to the right.
Then the forces cancel.
Therefore the correct answer is C. Therefore the net force on each wire is zero
