Two light identical springs of spring constant k are attached horizontally at the two ends of a uniform horizontal rod AB of length l and mass m. The rod is pivoted at its centre O and can rotate freely in horizontal plane. The other ends of the two springs are fixed to rigid supports as shown in figure.The rod is gently pushed through a small angle and released. The frequency of resulting oscillation is

• A. \(\frac{1}{{2{\rm{\pi }}}}\sqrt {\frac{{2{\rm{k}}}}{{\rm{m}}}} \)
• B. \(\frac{1}{{2{\rm{\pi }}}}\sqrt {\frac{{3{\rm{k}}}}{{\rm{m}}}} \)
• C. \(\frac{1}{{2{\rm{\pi }}}}\sqrt {\frac{{6{\rm{k}}}}{{\rm{m}}}} \)
• D. \(\frac{1}{{2{\rm{\pi }}}}\sqrt {\frac{{\rm{k}}}{{\rm{m}}}} \)