Step 1: Understanding the SHM Equation
The displacement equation for SHM is given as:
\[
y = A \sin (\omega t + \phi)
\]
Where:
- \( y \) is the displacement,
- \( A \) is the amplitude,
- \( \omega \) is the angular frequency,
- \( t \) is the time,
- \( \phi \) is the phase constant.
The given displacement equation is:
\[
y = 2 \sin \left( \frac{\pi}{2} + \phi \right) \, \text{cm}
\]
Here, the amplitude \( A = 2 \) cm, and the angular frequency \( \omega \) is \( \frac{\pi}{2} \).
Step 2: Formula for Maximum Acceleration
The acceleration in SHM is given by:
\[
a = -\omega^2 y
\]
The maximum acceleration occurs when \( y = A \), so:
\[
a_{\text{max}} = \omega^2 A
\]
Step 3: Substituting the Known Values
We know that:
- \( A = 2 \, \text{cm} \)
- \( \omega = \frac{\pi}{2} \)
Now, substituting these values into the formula for maximum acceleration:
\[
a_{\text{max}} = \left( \frac{\pi}{2} \right)^2 \times 2
\]
Simplifying:
\[
a_{\text{max}} = \frac{\pi^2}{4} \times 2 = \frac{\pi^2}{2} \, \text{cm/sec}^2
\]
Step 4: Conclusion
The maximum acceleration of the particle is \( \frac{\pi^2}{2} \, \text{cm/sec}^2 \), which corresponds to:
\[
\boxed{(A)} \, \frac{\pi^2}{2} \, \text{cm/sec}^2
\]