A pendulum of mass m and length L is connected to a spring as shown in figure. If the bob is displaced slightly from its mean position and released, it performs simple harmonic motion. The angular frequency of the oscillation of bob is 

• A

  $\sqrt{\frac{\mathrm{g}}{\mathrm{L}}}$

• B

  $\sqrt{\frac{{\mathrm{Kh}}^2+\mathrm{mgL}}{{\mathrm{mL}}^2}}$

• C

  $\sqrt{\frac{3\mathrm{g}}{\mathrm{L}}}$

• D

  $\sqrt{\frac{{\mathrm{Kh}}^2}{{\mathrm{mL}}^2}}$