If the variance 1,2,3,4,5....10 is $ \large\frac{99}{12}$ then the standard deviation of 3,6,9,12....30 is

Question

$\begin {array} {1 1} (A)\;\large\frac{297}{4} & \quad (B)\;\large\frac{3}{2}\sqrt{33} \\ (C)\;\large\frac{3}{2}\sqrt{99} & \quad (D)\;\sqrt{\large\frac{99}{12}} \end {array}$