Three long, straight, parallel wires labeled Wire 1, Wire 2, and Wire 3 lie in the xy-plane and carry equal currents \(I\) directed out of the page in the \(+z\)-direction. Wire 1 is fixed at \(x = 0\), Wire 2 is fixed at \(x = d\), and Wire 3 is fixed at \(x = 3d\). Which of the following correctly pairs the ratio of the magnitude of the net magnetic force per unit length on Wire 1 to that on Wire 3, \(F_1 / F_3\), with the magnitude of the net magnetic field at the midpoint between Wire 1 and Wire 2?