An electron of mass m and charge e is accelerated from rest through a potential difference V in vacuum. The final speed of the electron will be 

• A

  $\mathrm{V}\sqrt{\mathrm{e}/\mathrm{m}}$

• B

  $\sqrt{\mathrm{eV}/\mathrm{m}}$

• C

  $\sqrt{2\mathrm{eV}/\mathrm{m}}$

• D

  $2\mathrm{eV}/\mathrm{m}$