(P) Aryl aldoxime + aq NaOH (no acetylation). Deprotonation of the oxime OH and subsequent E2-like loss of water with intramolecular displacement of the ortho-Br by the resulting phenoxide gives 5-nitro-2-hydroxybenzonitrile (an aryl cyanide with an ortho-OH). The –Br is replaced by –OH and the CH=NOH is dehydrated to –C$\equiv$N. P $\to$ 1.

(Q) Same aldoxime, first acetylated (Ac${}_2$O) then treated with Na${}_2$CO${}_3$. The mild base only performs E2 elimination of OAc to give the aryl nitrile, but does not have enough hydroxide character to displace the ortho-Br. The product retains the bromide: 2-bromo-5-nitrobenzonitrile. Q $\to$ 2.

(R) Aryl methyl ketoxime + aq NaOH. With a methyl group on the oxime carbon (no $\alpha$-H suitable for elimination as a nitrile), the ortho-Br is displaced by the deprotonated oxime oxygen via intramolecular S${}_{\text{N}}$Ar, forming a five-membered O–N ring fused to the benzene ring: 3-methyl-5-nitro-1,2-benzisoxazole. R $\to$ 4.

(S) O-Acetyl ketoxime + aq Na${}_2$CO${}_3$. Mild base hydrolyses the O-acetyl group, regenerating the free oxime (E/Z tautomer of the starting material). No further cyclisation or Beckmann rearrangement occurs under these mild conditions. S $\to$ 5.

Mapping P $\to$ 1, Q $\to$ 2, R $\to$ 4, S $\to$ 5 corresponds to option (B).