An object of mass $m$ is suspended at the end of a massless wire of length $L$ and area of cross-section $A$. The Young's modulus of the material of the wire is $Y$. If the mass is pulled down slightly,its frequency of oscillation along the vertical direction is:

• A
  $f = \frac{1}{2 \pi} \sqrt{\frac{YA}{mL}}$
• B
  $f = \frac{1}{2 \pi} \sqrt{\frac{YL}{mA}}$
• C
  $f = \frac{1}{2 \pi} \sqrt{\frac{mA}{YL}}$
• D
  $f = \frac{1}{2 \pi} \sqrt{\frac{mL}{YA}}$