If ${a^2},\;{b^2},\;{c^2}$ are in $A.P.$, then ${(b + c)^{ - 1}},\;{(c + a)^{ - 1}}$ and ${(a + b)^{ - 1}}$ will be in

  • A

    $H.P.$

  • B

    $G.P.$

  • C

    $A.P.$

  • D

    None of these

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