A copper wire is pulled so that its diameter decreases from $1.0\,\text{mm}$ to a constant $0.5\,\text{mm}$. The resistance of the original copper wire is $0.2\,\Omega$. What is the resistance of the stretched wire?
- A$0.4\,\Omega$
- B$0.8\,\Omega$
- C$1.6\,\Omega$
- D$3.2\,\Omega$