From Ampere's circuital law, $B = \frac{\mu_0 I}{2\pi R^2} \cdot r$ if $r < R \Rightarrow B_{inside} \propto r$. $B = \frac{\mu_0 I}{2\pi r}$ if $r \geq R \Rightarrow B_{outside} \propto \frac{1}{r}$. Hence the correct plot of magnetic field B with distance r from axis of cable is given as shown in the diagram.