In the Bohr model of a hydrogen atom, the centripetal force is furnished by the coulomb attraction between the proton and the electron. If \[{{a}_{0}}\] is the radius of the ground state orbit, m is he mass, e is the charge on the electron and \[{{\varepsilon }_{0}}\] is the vacuum permittivity, the speed of the electron is

• A.  0
• B. \[\frac{e}{\sqrt{{{\varepsilon }_{0}}a{{  }_{0}}m}}\]
• C. \[\frac{e}{\sqrt{4\pi {{\varepsilon }_{0}}a{{  }_{0}}m}}\]       
• D. \[\frac{\sqrt{4\pi {{\varepsilon }_{0}}a{{  }_{0}}m}}{e}\]