If m is the A.M of two distinct real numbers l and $n(l,n > 1)$ and $G_1, G_2$ and $G_3$ are three geometric means between l and n, then $G_1 ^4 +2 G_2^4+G_3^4$ equals.

Question

$\begin{array}{1 1} 4lm^2n \\ 4 lmn^2 \\ 4l^2m^2n^2 \\ 4l^2mn \end{array}$