Read the paragraph and chose the correct answer of the following questions In young experiment position of bright fringes is given by $\mathrm{x}=\mathrm{n} \lambda(\mathrm{D} / \mathrm{d})$ and the position of dark fringes is given by $\mathrm{x}=(2 \mathrm{n}-1)(N 2)(\mathrm{D} / \mathrm{d})$ where $\mathrm{n}=1,2,3 \ldots \ldots \ldots \ldots$ for first
second, third bright/dark fringe. The center of the fringe pattern is bright (for $\mathrm{n}=0$ ). The width of each bright/dark fringe is $\beta=(\lambda \mathrm{D} / \mathrm{d})$, Where $\lambda=5000 \AA$. Slits are $0.2 \mathrm{~cm}$
apart and $\mathrm{D}=1 \mathrm{~m}$
(i) If light of wavelength $6000 \AA$ be used in the above experiment the fringe width would be $\mathrm{mm}$
(A) $0.30$
(B) 3
(C) $0.6$
(D) 6
(ii) with the light of wavelength $5000 \AA$, If experiment were carried out under water of a $n=(4 / 3)$ the fringe width would be
(A) zero
(B) $(4 / 3)$ times
(C) (3/4) times
(D) none of these