The circum radius of the triangle formed by the points $(2,-1,1),(1,-3,-5)$ and $(3,-4,-4)$ is

• A

  $\frac{\sqrt{35}}{2}$
• B

  $\frac{\sqrt{25}}{3}$
• C

  $\sqrt{41}$
• Correct answer
  D

  $\frac{\sqrt{41}}{2}$

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