A very long, hollow cylindrical conductor has an inner radius \(a\) and an outer radius \(b\). The conductor carries a steady current directed parallel to its central axis with a non-uniform volume current density given by \(J(r) = \dfrac{C_0}{r}\) for \(a \le r \le b\), where \(C_0\) is a positive constant and \(r\) is the radial distance from the central axis. The region \(r < a\) is empty space. Which of the following graphs best represents the magnitude of the magnetic field \(B\) as a function of \(r\) from \(r = 0\) to \(r > b\)?