Step 1: Understanding the structure of the compound.
The given compound is \( \text{CH}_3\text{CH}_2\text{C}\, \text{NH}_2 \), where an amine group \( \text{NH}_2 \) is attached to a carbon chain.
Step 2: Analysis of options.
(A) Primary amine: A primary amine is an amine where the nitrogen atom is attached to one carbon atom. In this case, the nitrogen is attached to a single carbon chain, making it a primary amine.
(B) Secondary amine: A secondary amine has two alkyl groups attached to the nitrogen atom. This is not the case here.
(C) Tertiary amine: A tertiary amine has three alkyl groups attached to the nitrogen atom. This is not applicable here.
(D) Quaternary salt: A quaternary salt involves a positively charged nitrogen atom attached to four groups, which is not the case here.
Step 3: Conclusion.
The correct answer is (A) because the given compound is a primary amine.