Periodic time of simple pendulum is given by

• A. \(2\pi \sqrt {\frac{l}{g}}\)
• B. \(2\pi \sqrt {\frac{g}{l}} \)
• C. \(\frac{1}{{2\pi }}\sqrt {\frac{g}{l}} \)
• D. \(\frac{1}{{2\pi }}\sqrt {\frac{l}{g}}\)