The slope of the common tangent drawn to the circles $x^2+y^2-4 x+12 y-216=0$ and $x^2+y^2+6 x-12 y+36=0$ is

• A

  $1$
• B

  $-1$
• Correct answer
  C

  $\frac{5}{12}$
• D

  $\frac{12}{7}$

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