Students measure the magnetic field magnitude \(B\) along the central axis of a circular wire loop of radius \(R\) carrying a steady current \(I\), as a function of the axial distance \(z\) from the center of the loop.

According to the Biot-Savart law, the on-axis magnetic field is given by
\[ B(z) = \dfrac{\mu_0 I R^2}{2(R^2 + z^2)^{3/2}} \]

The students wish to construct a single linear graph using all their data points (\(z \ge 0\)) to confirm this functional relationship, which approaches the inverse-cube dipole dependence \(B \propto z^{-3}\) for \(z \gg R\). Which of the following pairs of quantities should be plotted on the vertical and horizontal axes to produce a linear graph, and what relationship correctly yields the radius \(R\) from the vertical intercept \(b\) and slope \(m\) of the best-fit line?