Two particles of equal mass $m$ and equal charge $q$ are separated by a distance of $16 \text{ cm}$. They do not experience any net force. The value of $\frac{q}{m}$ is . . . . . . (where $G$ is the universal gravitational constant and $\epsilon_0$ is the permittivity of free space).

• A
  $\sqrt{4 \pi \epsilon_0 G}$
• B
  $\sqrt{\frac{G}{4 \pi \epsilon_0}}$
• C
  $\sqrt{\frac{\pi \epsilon_0}{G}}$
• D
  $\sqrt{4 \pi \epsilon_0 g}$