The resistance of a platinum wire at $0^{\circ }\text{C}$ is $2\Omega$ and $6.8\Omega$ at $80^{\circ }\text{C}$. The temperature coefficient of resistance of the wire is:

1. A
   $4\times 10^{-2}{}^{\circ }{\text{C}}^{-1}$
2. B
   $3\times 10^{-3}{}^{\circ }{\text{C}}^{-1}$
3. C
   $3\times 10^{-2}{}^{\circ }{\text{C}}^{-1}$
4. D
   $1\times 10^{-1}{}^{\circ }{\text{C}}^{-1}$