If A.M of $x_1, x_2....x_n$ is $\overline x$ then A.M of $ax_1+b, ax_2+b, ax_3+b...ax_4+b$ is

Question

$\begin {array} {1 1} (A)\;a\overline x & \quad (B)\;a\overline x+b \\ (C)\;a\overline x+nb & \quad (D)\;None\: of \: these \end {array}$