Name the aliphatic amine with one nitrogen atom and three carbon atoms.

The correct name for an aliphatic amine with one nitrogen atom and three carbon atoms is trimethylamine. This compound is classified as a tertiary amine, where the nitrogen atom is bonded to three carbon atoms and no hydrogen atoms. In this case, "tri-" indicates that there are three groups attached to the nitrogen.

To break it down further, trimethylamine is derived from ammonia (NH3) by replacing all three hydrogen atoms with methyl groups (−CH3). This results in a nitrogen atom with three adjacent carbon atoms, making it a simple structure representative of this category of amines.

This is distinct from ethylamine, which has only two carbon atoms attached to the nitrogen, and propylamine, which has three carbon atoms, but is a primary amine with only one carbon chain directly connected to the nitrogen, along with two hydrogen atoms. Diethylamine is a secondary amine with two ethyl groups and one hydrogen attached to the nitrogen. Thus, the nomenclature of trimethylamine clearly describes a nitrogen atom bonded to three carbon-containing groups, aligning with the question's description.