An electric current flows along an insulated strip PQ of a metallic conductor. The current density in the strip varies as shown in the graph. Which one of the following statements could explain this variation?

The current density at P is higher than at Q.For the same current flowing through the metallic conductor PQ, the cross-sectional area at P is narrower than at Q.The resistance per unit length r is given by $\mathrm{r}=\frac{\mathrm{\rho }}{\mathrm{A}}$ where $\rho$ is the resistivity and A is the cross-section area of the conductor PQ. Thus, r is inversely proportional to the cross-sectional area A of the conductor.