Acetone ($\mathrm{CH_3COCH_3}$) reacts with HCN to give a product. Which is the correct product?

1. NCERT §8.4 (Nucleophilic addition reactions): aldehydes and ketones react with HCN (in the presence of catalytic base to generate $\mathrm{CN^-}$) to form CYANOHYDRINS. 2. The mechanism: $\mathrm{CN^-}$ attacks the electrophilic carbonyl carbon; the resulting alkoxide is protonated to give the cyanohydrin. 3. For acetone, $\mathrm{(CH_3)_2C{=}O} + \mathrm{HCN} \to \mathrm{(CH_3)_2C(OH)(CN)}$. 4. Structurally, the cyanohydrin has both an $\mathrm{OH}$ (from the former $\mathrm{C{=}O}$ oxygen + protonation) and a $\mathrm{CN}$ group on the SAME carbon. 5. Option B requires the loss of water — not the addition reaction here. Option C has the wrong substitution pattern. Option D would require dehydration that's not part of the simple cyanohydrin step. _Source: NCERT Class 12 Chemistry Part 2, Ch 8, §8.4 (Nucleophilic addition — cyanohydrin formation), p. 9–10._