In $\Delta ABC$ the mid-points of the sides AB,BC and CA are respectively $(l,0,0),(0,m,0)$ and $(0,0,n).$ Then $\large\frac{AB^2+BC^2+CA^2}{l^2+m^2+n^2}=$

Question

\[\begin {array} {1 1} (1)\;2 & \quad (2)\;4 \\ (3)\;8 & \quad (4)\;16 \end {array}\]