Consider the circles $x^2+y^2+2 a x+c=0$ and $x^2+y^2+2 b y+c=0$. The two circles touch each other if

• A

  $c=\sqrt{a^2+b^2}$
• Correct answer
  B

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

  $c=\frac{1}{a^2}+\frac{1}{b^2}$
• D

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

Hence, the correct answer is option: 'B'.