“龟鹤同池，龟鹤共100只，共有脚350只，问龟鹤各多少只？”设龟有x只，鹤有y只，则下列方程组中正确的是（　　）

A：$\left\{\begin{array}{c}x+y=100\\ 2x+4y=350\end{array}\right.$

B：$\left\{\begin{array}{c}x+y=100\\ 4x+2y=350\end{array}\right.$

C：$\left\{\begin{array}{c}x-y=100\\ 4x+2y=350\end{array}\right.$

D：$\left\{\begin{array}{c}x-y=100\\ 2x+4y=350\end{array}\right.$