In the Bohr model of H-atom, an electron (e) is revolving around a proton (p) with velocity v, if r is the radius of orbit and m is mass and $\varepsilon_{0}$ is vacuum permittivity, the value of v is :

Question

( A ) $\large\frac{e}{\sqrt{4 \pi m \in_0 r}}$
( B ) $\large\frac{e}{\sqrt{\pi m \in_0 r}}$
( C ) $\large\frac{2e}{\sqrt{\pi m \in_0 r}}$
( D ) $\large\frac{e}{4 \pi m \in_0 r}$