In a Young's double slit experiment, the fringe width will remain same, if (D = distance between screen and plane of slits, d = separation between two slits and $\mathrm{\lambda }$ =  wavelength of light used)

• A

  Both $\mathrm{\lambda }$ and D are doubled

• B

  Both d and D are doubled

• C

  D is doubled but d is halved

• D

  $\mathrm{\lambda }$ is doubled but d is halved