Step 1: Formula for Time Period in SHM
The time period \( T \) of a simple harmonic oscillator is given by:
\[
T = 2\pi \sqrt{\frac{m}{k}}
\]
where:
- \( m = 4 \) kg (mass of the body),
- \( k = 64 \) N/m (force constant of the spring).
Step 2: Substituting Values
\[
T = 2\pi \sqrt{\frac{4}{64}}
\]
\[
= 2\pi \sqrt{\frac{1}{16}}
\]
\[
= 2\pi \times \frac{1}{4}
\]
\[
= \frac{\pi}{2}
\]
Conclusion
Thus, the correct answer is:
\[
\frac{\pi}{2} \text{ s}
\]