(P) Cyclohexene route: Ozonolysis (reductive, Zn) opens the ring to give hexanedial (OHC-(CH${}_2$)${}_4$-CHO). Intramolecular aldol with aq. NaOH/$\Delta$ closes to cyclopent-1-enecarbaldehyde. Protect the -CHO as cyclic acetal (ethylene glycol/PTSA). Hydroboration-oxidation of the ring alkene (BH${}_3$ then H${}_2$O${}_2$/NaOH) gives anti-Markovnikov syn alcohol on the ring. Acid hydrolysis unmasks the aldehyde, and finally NaBH${}_4$ reduces it to a -CH${}_2$OH. The product is 2-(hydroxymethyl)cyclopentan-1-ol. P $\to$ 3.

(Q) 1-Methylcyclohexene route: Same sequence; ozonolysis cleaves the trisubstituted alkene to give a keto-aldehyde. Intramolecular aldol followed by acetal protection of the ketone, then hydroboration-oxidation gives the secondary ring alcohol, deprotection, NaBH${}_4$ reduces the ketone (or aldehyde, depending on the case) to alcohol. The product carries -CH(OH)CH${}_3$ side chain on a ring next to an -OH. Q $\to$ 5.

(R) 2-Methylcyclopent-2-enone (R): Protect ketone as ketal. Oxymercuration of the alkene gives the Markovnikov tertiary alcohol adjacent to the ketal. NaBH${}_4$ demercurates. Hydrolysis returns the ketone, NaBH${}_4$ then reduces it to a secondary alcohol on the ring carbon next to the tertiary -OH. Product has tertiary -OH and adjacent -OH with methyl on the tertiary carbon. R $\to$ 4.

(S) 2-Methylcyclopent-2-enone (same start as R but with hydroboration): Ketal protection, hydroboration-oxidation gives anti-Markovnikov secondary alcohol (away from the methyl), hydrolysis regenerates the ketone, NaBH${}_4$ reduces it. The result is 2-methylcyclopentane-1,3-diol. S $\to$ 1.

$\therefore$ Option (A): P-3, Q-5, R-4, S-1.