If $(a, b)$ is the common point for the circles $x^2+y^2-4 x+4 y-1=0$ and $x^2+y^2+2 x-4 y+1=0$, then $a^2+b^2=$

• Correct answer
  A

  $\frac{1}{5}$
• B

  5
• C

  25
• D

  $\frac{1}{25}$

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