$\begin {array} {1 1} (A)\;\large\frac{x^2}{49}-\large\frac{y^2}{343}=1 & \quad (B)\;\large\frac{9x^2}{343}-\large\frac{y^2}{49}=1 \\ (C)\;\large\frac{x^2}{49}+\large\frac{9y^2}{343}=1 & \quad (D)\;\large\frac{9x^2}{343}+\large\frac{y^2}{49}=1 \end {array}$