A boy ties a stone of mass $100 \mathrm{g}$ to the end of a $2 \mathrm{m}$ long string and whirls it around in a horizontal plane. The string can withstand the maximum tension of $80 \mathrm{N}$. If the maximum speed with which the stone can revolve is $\frac{K}{\pi } \mathrm{rev} {\min }^{-1}$. The value of $K$ is :
(Assume the string is massless and un-stretchable)

• A

  $400$
• B

  $300$
• Correct answer
  C

  $600$
• D

  $800$

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