If circles ${x^2} + {y^2} + 2ax + c = 0$and ${x^2} + {y^2} + 2by + c = 0$ touch each other, then 

  • A

    $\frac{1}{a} + \frac{1}{b} = \frac{1}{c}$

  • B

    $\frac{1}{{{a^2}}} + \frac{1}{{{b^2}}} = \frac{1}{{{c^2}}}$

  • C

    $\frac{1}{a} + \frac{1}{b} = {c^2}$

  • D

    $\frac{1}{{{a^2}}} + \frac{1}{{{b^2}}} = \frac{1}{c}$

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