d
\(\mathrm{RCHO}+\ddot{\mathrm{NH}_{2}} \rightarrow \mathrm{RCH}=\mathrm{N}-\mathrm{NH}_{2}+\mathrm{H}_{2} \mathrm{O}\)

In the above reaction \(-\ddot{\mathrm{NH}}_{2}\) as nucleophilic species which adds on carbon. Therefore this is the case of the nucleophilic addition reaction. Simultaneously, a mole of \(\mathrm{H}_{2} \mathrm{O}\) also eliminated. Therefore, overall this reaction is a nucleophilic addition-elimination reaction.