A particle executes simple harmonic motion with an amplitude of $5 cm$ . When the particle is at $4 cm$ from the mean position, the magnitude of its velocity in $SI$ units is equal to that of its acceleration. Then, its periodic time in seconds is:

• Correct answer
  A

  $\frac{8\pi }{3}$
• B

  $\frac{3}{8}\pi$
• C

  $\frac{4\pi }{3}$
• D

  $\frac{7}{3}\pi$

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