A Plastic film of thickness t is placed in the path of one of the interfering wave in the young's double slit experiment and it is found that the central fringe is displaced through a width of 5 fringes . If wavelength of light used is $5890 \mathring{A}$ What is thickness of film used

Question

$(a)\;6.45 \times 10^{-4}\;m \\ (b)\;6.05 \times 10^{-4}\;m \\ (c)\;5.20 \times 10^{-4}\;m \\ (d)\;2.35 \times 10^{-4}\;m $