A cantilever beam of negligible weight is carrying a mass at its free end, and is also resting on an elastic support of stiffness $$k_1$$ as shown in the figure below.If $$k_2$$ represents the bending stiffness of the beam, the natural frequency (rad/s) of the system is

A

$$\frac {\sqrt {(k_1 k_2)}}{M} {(k_1 + k_2)}$$

B

$$\frac {{\sqrt 2 }(k_1 + k_2)}{M}$$

C

$$\frac {\sqrt {(k_1 + k_2)}}{M} $$

D

$$\frac {\sqrt {(k_1 - k_2)}}{M} $$