Racemization during hydrolysis with aqueous KOH indicates that the reaction proceeds via an $S_N1$ mechanism, which involves the formation of a planar carbocation intermediate. For a compound to undergo racemization, it must be chiral (optically active) and form a relatively stable carbocation (such as secondary, tertiary, benzylic, or allylic).

Compound (ii), 1-chloropropane ($\text{CH}_3\text{CH}_2\text{CH}_2\text{Cl}$), is an achiral primary alkyl halide. It typically undergoes $S_N2$ substitution and cannot exhibit racemization.

Since the structural formulas for compounds (i), (iii), and (iv) are missing from the provided text, their chirality and carbocation stability cannot be independently evaluated. Therefore, the exact correct option cannot be definitively verified.