Concept:A primary amine has the −NH2​ group directly attached to only one carbon atom.Explanation:Identify the number of carbon groups attached to the nitrogen atom in each option.A. N-methyl methanamine is (CH3​)2​NH, a secondary amine.B. Phenyl methanamine is C6​H5​CH2​NH2​.Here, the nitrogen is bonded to one alkyl group and two hydrogen atoms, so it is a primary amine.C. N-phenyl benzenamine is (C6​H5​)2​NH, a secondary amine.D. N-methyl benzenamine is C6​H5​NHCH3​, a secondary amine.Only phenyl methanamine fits the primary amine condition.
