As we know that time period for a pendulum is,
[tex]\begin{gathered} T=2\pi\sqrt[\placeholder{⬚}]{\frac{l}{g}} \\ Here, \\ l=10m \\ g=9.8\text{ m/s}^2 \\ So, \\ T=2\times3.14\sqrt[\placeholder{⬚}]{\frac{10}{9.8}}=6.343s \\ \end{gathered}[/tex]So 3rd option is correct option.
