One end of a spring of force constant $k$ is fixed to a vertical wall and the other to a block of mass $m$ resting on a smooth horizontal surface. There is another wall at a distance $x_0$, from the block. The spring is then compressed by $2x_0$ and released. The time taken by the block to strike the other wall is

• A

  $\frac{1}{6}\pi \sqrt{\frac{m}{k}}$
• B

  $\sqrt{\frac{m}{k}}$
• Correct answer
  C

  $\frac{2\pi }{3}\sqrt{\frac{m}{k}}$
• D

  $\frac{\pi }{4}\sqrt{\frac{m}{k}}$

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