Read the passage carefully and answer the Questions.

Alcohols and phenols are obtained when a hydrogen atom in aliphatic and aromatic hydrocarbons respectively, is replaced by - OH group. These compounds find wide applications in industry as well as in our daily life. You may notice that ordinary spirit is used for polishing wooden furniture which is chiefly a compound containing hydroxyl group. An alcohol contains one or more hydroxyl (OH) group(s) directly attached to carbon atom(s), of an aliphatic system ($CH_3OH$) while a phenol contains -OH group(s) directly attached to carbon atom(s) of an aromatic system ($C_6H_5OH$). Alcohols are prepared by the hydration of alkenes, fermentation of glucose, and reduction of carbonyl compounds. Alcohols produce alkenes upon dehydration whereas alkenes on acid catalyzed hydration convert into alcohols.

An alkyl halide can be converted into alcohol through

substitution

The correct answer is Option (3) → substitution

Alkyl halides (R–X) are converted to alcohols (R–OH) by nucleophilic substitution reactions, where the halide (X) is replaced by the hydroxide ion (OH⁻).

Common methods:

• Aqueous KOH or NaOH (SN1 or SN2 depending on the alkyl halide).
• Moist Ag₂O or AgNO₃ (promotes ionization for SN1-like).

The reaction is: R–X + OH⁻ → R–OH + X⁻

This is a classic substitution reaction (not addition, elimination, or dehydrohalogenation).

• Addition: Occurs with unsaturated compounds (e.g., alkenes).
• Elimination/Dehydrohalogenation: Converts alkyl halides to alkenes (e.g., alcoholic KOH).
• The passage mentions hydration (addition to alkenes) and dehydration (elimination from alcohols), but the reverse conversion (alkyl halide → alcohol) is substitution.

Thus, the correct answer is substitution.