Which from following compounds is an example of primary amines?

A primary amine has the nitrogen atom bonded to one alkyl or aryl group and two hydrogen atoms.

N-methylmethanamine: Contains a methyl group substitution on nitrogen, resulting in the structure $\mathrm{CH_3-NH-CH_3}$, making it secondary.

4-Bromobenzenamine: Consists of a single aryl group and two hydrogens on nitrogen, conforming to $\mathrm{Ar-NH_2}$, hence primary.

N-Phenylbenzenamine: Nitrogen bonds to two aryl groups as $\mathrm{C_6 H_5-NH-C_6 H_5}$, classifying it as secondary.

N-Ethyl-N-methylpropan-2-amine: The structure is $\mathrm{(CH_3)2CH-N(CH_3)(C_2H_5)}$ with three alkyl groups attached, rendering it tertiary.