If the circle $S \equiv x^2+y^2+2 g x+4 y+1=0$ bisects the circumference of the circle $\mathrm{x}^2+\mathrm{y}^2-2 \mathrm{x}-3=0$, then the radius of circle $\mathrm{S}=0$ is

• A

  5
• Correct answer
  B

  $\sqrt{12}$
• C

  25
• D

  12

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