18. Two very long current-carrying wires are shown end on in the figure. The wire on the left has a 4A current going into the plane of the paper and the wire on the right has a 3A current coming out of the paper.
Disregarding the case of x→∞, in which region(s) could the magnetic field from these two wires add to zero on the x -axis.
A) Region I only
B) Region II only
C) Region III only
D) Regions I and III only