Reaction of a carbonyl compound with one of the following reagents involves nucleophilic addition followed by elimination of water. The reagent is:

Reagents like hydrazine (${\text{NH}}_2{\text{NH}}_2$), hydroxylamine, or primary amines react with carbonyl compounds via nucleophilic addition to the $>\text{C}=\text{O}$ group followed by the elimination of a water molecule to form a $>\text{C}=\text{N}-$ bond (hydrazone, oxime, etc.).$\text{HCN}$, ${\text{NaHSO}}_3$, and Grignard reagents only undergo addition without elimination of water.