If variance of $x_1, x_2,....x_n$ is $\sigma^2$ then variance of $ax_1, ax_2,.....ax_n ( a \neq 0)$ is

Question

$\begin {array} {1 1} (A)\;\sigma^2 & \quad (B)\;a \sigma^2 \\ (C)\;a^2 \sigma^2 & \quad (D)\;\large\frac{\sigma^2}{a^2} \end {array}$