$A$ simple pendulum of length $L$ is placed between the plates of a parallel plate capacitor having an electric field $E,$ as shown in the figure. Its bob has mass $m$ and charge $q.$ The time period of the pendulum is given by:

• A
  $2\pi \sqrt {\frac{L}{{\sqrt {{g^2}\, - \,\frac{{{q^2}{E^2}}}{{{m^2}}}} }}} $
• B
  $2\pi \sqrt {\frac{L}{{\left( {g\, + \,\frac{{qE}}{m}} \right)}}} $
• C
  $2\pi \sqrt {\frac{L}{{\left( {g\, - \,\frac{{qE}}{m}} \right)}}} $
• D
  $2\pi \sqrt {\frac{L}{{\sqrt {{g^2}\, + \,{{\left( {\frac{{qE}}{m}} \right)}^2}} }}} $