The slope of one of the direct common tangents drawn to the circles $x^2+y^2-2 x+4 y+1=0$ and $x^2+y^2-4 x-2 y+4=0$ is

• A

  $0$
• Correct answer
  B

  $\frac{4}{3}$
• C

  $\frac{3}{4}$
• D

  $1$

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