Given below are two statements: Statement I: The conversion proceeds well in the less polar medium.
$$\mathrm{CH_3-CH_2-CH_2-CH_2-Cl} \;\xrightarrow{\;\;HO^-\;\;} \mathrm{CH_3-CH_2-CH_2-CH_2-OH} + \mathrm{Cl^{(-)}}$$
Statement II: The conversion proceeds well in the more polar medium.

In the light of the above statements, choose the correct answer from the options given below

The substrate is 1-chlorobutane, $$\mathrm{CH_3CH_2CH_2CH_2Cl}$$, a primary alkyl chloride. Its replacement by the strongly basic hydroxide ion takes place through nucleophilic substitution.

Case 1: Less-polar, polar-aprotic medium
• In solvents such as acetone, DMSO or DMF the medium is polar enough to keep the ionic reagent $$HO^-$$ in solution, yet it is aprotic and therefore cannot hydrogen-bond to the anion.
• Because the nucleophile is not strongly solvated, its effective basicity/nucleophilicity is high and the reaction proceeds by a single-step $$S_N2$$ pathway: $$HO^-$$ attacks the backside of the carbon bearing chlorine and displaces $$Cl^-$$ in one concerted transition state.
• Primary halides give very fast $$S_N2$$ reactions under these conditions, so the conversion is “best” (fastest and highest-yield) in a comparatively less-polar (but still polar-aprotic) medium. Hence Statement I is correct.

Case 2: Highly polar, protic (aqueous) medium
• In water or aqueous ethanol the dielectric constant is very high (≈ 80 for water). Such a medium stabilises the charged species that develop in the transition state of any ionic process (the leaving chloride ion as well as the entering hydroxide ion).
• Although the hydroxide ion is partially hydrogen-bonded (which lowers its free nucleophilicity), the excellent solvation of the substrate’s partial charges lowers the activation energy enough for the reaction to proceed smoothly. In laboratory practice ordinary dilute aqueous NaOH or KOH is routinely used to convert primary alkyl chlorides to alcohols in good yield.
• Thus, even in a highly polar medium the reaction works well; it is simply somewhat slower than in the aprotic case. Therefore Statement II is also correct.

Because both statements describe circumstances under which the given substitution takes place efficiently, they are simultaneously true.

Hence the correct choice is:
Option A which is: Both Statement I and Statement II are true.