In a certain double slit experimental arrangement, interference fringes of width 1 mm each are observed when light of wavelength 5000 Å is used. Keeping the set up unaltered, if the source is replaced by another of wavelength 6000 Å, the fringe width will be
(a) 1.2 mm
(b) 0.5 mm
(c) 1 mm
(d) 1.5 mm
