An electron enters the space between the plates of a charged capacitor as shown. The charge density on the plate is $\sigma$. Electric intensity in the space between the plates is $E$. $A$ uniform magnetic field $B$ also exists in that space perpendicular to the direction of $E$. The electron moves perpendicular to both $\vec{E}$ and $\vec{B}$ without any change in direction. The time taken by the electron to travel a distance $\ell$ in the space is

• A
  $\frac{\sigma \ell}{\varepsilon_0 B}$
• B
  $\frac{\sigma B}{\varepsilon_0 \ell}$
• C
  $\frac{\varepsilon_0 \ell B}{\sigma}$
• D
  $\frac{\varepsilon_0 \ell}{\sigma B}$