A stone tide to a string of length $L$ is whirled in a vertical circle with the other end of the string at the centre. At a certain instant of time, the stone is at its lowest position and has a speed $u$. The magnitude of change in its velocity, as it reaches a position where the string is horizontal, is $\sqrt{x\left(u^2-gL\right)}$. The value of $x$ is

• Correct answer
  A

  $2$
• B

  $3$
• C

  $4$
• D

  $1$

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