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 $G_1^4 + 2G_2^4 + G_3^4$ equals :

  • [JEE MAIN 2015]
  • A

    $4{l^2}{m^2}{n^2}$

  • B

    $4{l^2}mn$

  • C

    $4l{m^2}n$

  • D

    $4lm{n^2}$

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