If $a,b,c$ are in $A.P.$, then $\frac{1}{{\sqrt a + \sqrt b }},\,\frac{1}{{\sqrt a + \sqrt c }},$ $\frac{1}{{\sqrt b + \sqrt c }}$ are in

  • A

    $A.P.$

  • B

    $G.P.$

  • C

    $H.P.$

  • D

    None of these

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