A pendulum is hung from the roof of a sufficiently high building and is moving freely to and fro like a simple harmonic oscillator. The acceleration of the bob of the pendulum is $20{\text{m/s}}^2$ at a distance of $5\text{m}$ from the mean position. The time period of oscillation is:

1. A
   $2\text{s}$
2. B
   $\pi \text{s}$
3. C
   $2\pi \text{s}$
4. D
   $1\text{s}$