The A.M of $nC_0, \: nC_1, nC_2.......nC_n$ is

Question

$\begin {array} {1 1} (A)\;\large\frac{2^n}{n+1} & \quad (B)\;\large\frac{2^n}{n} \\ (C)\;\large\frac{2^{n-1}}{n+1} & \quad (D)\;None \: of \: these \end {array}$