$A$ solid sphere of radius $R$ carries a positive charge $Q$ distributed uniformly throughout its volume. $A$ very thin hole is drilled through its center. $A$ particle of mass $m$ and charge $-q$ performs simple harmonic motion about the center of the sphere in this hole. The frequency of oscillation is

• A
  $\frac{1}{2 \pi}\left[\frac{Q q}{4 \pi \varepsilon_0 R^3 m}\right]^{\frac{1}{2}}$
• B
  $\frac{1}{2 \pi}\left[\frac{Q q}{4 \pi \varepsilon_0 R^2 m}\right]^{\frac{1}{2}}$
• C
  $\frac{1}{2 \pi} \frac{Q}{\left[4 \pi \varepsilon_0 m R^3\right]^{-\frac{1}{2}}}$
• D
  $\frac{1}{2 \pi}\left[\frac{Q q}{4 \pi \varepsilon_0 m R}\right]^{\frac{1}{2}}$