Which of the following amines has imino functional group?

Primary amines contain an amino group ($-NH_2$).

Secondary amines contain an imino group ($> NH$).

Tertiary amines contain a tertiary nitrogen atom ($> N-$).

Ethyl amine (CH_3CH_2NH_2$) is a primary amine.<br><br>Trimethyl amine ($(CH_3)_3N$) is a tertiary amine.<br><br>Dimethyl amine ($(CH_3)_2NH$) is a secondary amine, hence it contains an imino group.<br><br>Aniline (C_6H_5NH_2$) is a primary amine.

Answer: Dimethyl amine