方程组 $\frac{x}{3}=\frac{y}{2}=x+y-4$的解是 $($　　 $)$

A． $\left\{\begin{array}{c}x=-3\\ y=-2\end{array}\right.$B． $\left\{\begin{array}{c}x=6\\ y=4\end{array}\right.$C． $\left\{\begin{array}{c}x=2\\ y=3\end{array}\right.$D． $\left\{\begin{array}{c}x=3\\ y=2\end{array}\right.$