The graph illustrates how the resistance of a uniform metal wire changes with length. The gradient of the graph is $G$. The wire has cross-sectional area $A$. Which expression could be used to find the resistivity of the metal in the wire?
- A$G \times A$
- B$\frac{G}{A}$
- C$\frac{A}{G}$
- D$G \times A^2$