Explanation:

- The period of a pendulum depends on its length and gravity.

- For a pendulum of length $L$ in meters, the period $T\approx 2\pi \sqrt{\frac{L}{g}}$, where $g\approx 9.8{\text{m/s}}^2$.

- Plug in $L=1$ m:

$$T\approx 2\pi \sqrt{\frac{1}{9.8}}\approx 2.01\text{s}$$

- Option 1: 6 s is too long, does not fit the calculation.

- Option 2: 4 s is also too long.

- Option 3: 2 s is very close to the calculated value.

- Option 4: 1 s is too short.