Two Long, Parallel Wires Carry Currents of Different Magnitudes $\sqrt { 2 }$

Two long, parallel wires carry currents of different magnitudes. If the amount of current in one of the wires is doubled, what happens to the magnitude of the force that each wire exerts on the other?

A) It is increased by a factor of 8.
B) It is increased by a factor of 4.
C) It is increased by a factor of 3.
D) It is increased by a factor of 2.
E) It is increased by a factor of $\sqrt { 2 }$