$S_1$ and $S_2$  in column I represent coherent point sources,  $S$ represents a point source. 
$\lambda =$  wavelength of light emitted by the sources.
 

	Column – I		Column – II
A)		P)	Number of maxima = 2
B)		Q)	Number of minima = 2
C)		R)	Number of maxima = 4
D)		S)	Number of minima = 4
		T)	Number of maxima = 7

$A-p, q; B-r, s; C-s, t; D-p$
(C) Virtual image of S will act as another source 
$\Delta x=d\sin \theta ,d=2\lambda$

For maximas,  $n\lambda =2\lambda \sin \theta \Rightarrow \sin \theta =\frac{n}{2}$
$n=0,1,2,$
 $\theta =0,{30}^{°},{90}^{°},{150}^{°}$
Total maximas possible =7 (centre +3 up +3 down)
(D)  $\Delta x=2\lambda \cos \theta ;\theta \le {60}^{°}$
For maximas,  $\Delta x=n\lambda \Rightarrow \cos \theta =\frac{n}{2}; n=0,1,2,\theta \ne {90}^{°}, \theta ={60}^{°},\theta =0^{°}$
Total maximas two, For minima,  $\Delta x=(2n-1)\frac{\lambda }{2}$;
$$\begin{gathered} \cos \theta =\frac{2n-1}{4} \\ n=1,\cos \theta =\frac{1}{4};\theta >{60}^{°};n=2, \end{gathered}$$

$\cos \theta =\frac{3}{4};\theta <{60}^{°};$  No. of possible minimas =1