Column I shows four situations of standard Young's double slit arrangement with the screen placed far away from the slits S$$_1$$ and S$$_2$$. In each of these cases, S$$_1$$P$$_0$$ = S$$_2$$P$$_0$$, S$$_1$$P$$_1$$ $$-$$ S$$_2$$P$$_1$$ = $$\lambda/4$$ and S$$_1$$P$$_2$$ $$-$$ S$$_2$$P$$_2$$ = $$\lambda/3$$, where $$\lambda$$ is the wavelength of the light used. In the cases B, C and D, a transparent sheet of refractive index $$\mu$$ and thickness t is pasted on slit S$$_2$$. The thickness of the sheets are different in different cases. The phase difference between the light waves reaching a point P on the screen from the two slits is denoted by $$\delta$$(P) and the intensity by I(P). Match each situation given in Column I with the statement(s) in Column II valid for that situation:
| Column I | Column II | ||
|---|---|---|---|
| (A) |  |
(P) | $$\delta ({P_0}) = 0$$ |
| (B) | $$(\mu-1)t=\lambda/4$$ |
(Q) | $$\delta ({P_1}) = 0$$ |
| (C) | $$(\mu-1)t=\lambda/2$$ |
(R) | $$I({P_1}) = 0$$ |
| (D) | $$(\mu-1)t=3\lambda/4$$ |
(S) | $$I({P_0}) > I({P_1})$$ |
| (T) | $$I({P_2}) > I({P_1})$$ |
The figure shows surface XY separating two transparent media, medium -1 and medium -2 . The lines ab and cd represent wavefronts of a light wave traveling in medium -1 and incident on X Y. The lines ef and gh represent wavefronts of the light wave in medium -2 after refraction.
Speed of the light is