In the given figure,a body of mass $M$ is held between two massless springs on a smooth inclined plane. The free ends of the springs are attached to firm supports. If each spring has a spring constant $k,$ the frequency of oscillation of the given body is:

• A
  $\frac{1}{2 \pi} \sqrt{\frac{k}{2M}}$
• B
  $\frac{1}{2 \pi} \sqrt{\frac{2k}{Mg \sin \alpha}}$
• C
  $\frac{1}{2 \pi} \sqrt{\frac{2k}{M}}$
• D
  $\frac{1}{2 \pi} \sqrt{\frac{k}{Mg \sin \alpha}}$