If the two lines of regression are $5x+3y=55$ and $7x+y=45$ then find the correlation coefficient between $x$ and $y$

Question

$\begin {array} {1 1} (A)\;-\sqrt{\large\frac{5}{21}} & \quad (B)\;\sqrt{\large\frac{5}{21}} \\ (C)\;\large\frac{5}{21} & \quad (D)\;None \: of \: these \end {array}$