What is the maximum acceleration of a particle performing $SHM$ given by the equation $y = 2\sin \left( {\frac{{\pi t}}{2} + \phi } \right)$,where $y$ is in $cm$?

• A
  $\frac{\pi }{2} \text{ cm/s}^2$
• B
  $\frac{{{\pi ^2}}}{2} \text{ cm/s}^2$
• C
  $\frac{\pi }{4} \text{ cm/s}^2$
• D
  $\frac{{{\pi ^2}}}{4} \text{ cm/s}^2$