A screen is placed at a certain distance from a narrow slit which is illuminated by a parallel beam of monochromatic light. If the wavelength of light used in the experiment is X, and d is the width of the slit, then angular width of central maximum will be

• A

  ${\sin }^{-1}(\mathrm{\lambda }/\mathrm{d})$

• B

  $2{\sin }^{-1}(\mathrm{\lambda }/\mathrm{d})$

• C

  ${\sin }^{-1}(2\mathrm{\lambda }/\mathrm{d})$

• D

  ${\sin }^{-1}(\mathrm{\lambda }/2\mathrm{d})$