A cable contains one thick copper wire strand and eight thin copper wire strands. These nine strands are all joined in parallel with one another. The cable’s cross-section is shown. Each thin strand has cross-sectional area $A$ and length $L$. The thick strand has cross-sectional area $4A$ and length $L$. The resistance of the complete cable is $R$. Which expression gives the resistivity of copper?
- A$\frac{4A}{33RL}$
- B$\frac{12A}{RL}$
- C$\frac{4AR}{L}$
- D$\frac{12AR}{L}$