One length of wire has a resistance of $16\,\Omega$. It measures $20\,\text{cm}$ in length and has a cross-sectional area of $2.0\,\text{mm}^2$. Which wire, made from the same material, would have a resistance of $8.0\,\Omega$?
- Alength $10\,\text{cm}$; cross-sectional area $1.0\,\text{mm}^2$
- Blength $10\,\text{cm}$; cross-sectional area $4.0\,\text{mm}^2$
- Clength $20\,\text{cm}$; cross-sectional area $1.0\,\text{mm}^2$
- Dlength $20\,\text{cm}$; cross-sectional area $4.0\,\text{mm}^2$