Which of the following is `3^(@)` amine?

Options

A. `CH_(3)-underset(NH_(2))underset(|)overset(CH_(3))overset(|)C-CH_(3)`
B. `CH_(2)-overset(H)overset(|)N-CH_(3)`
C. `CH_(3)-underset(NH_2)underset(|)N-CH_(3)`
D. `H_(2)C-underset(CH_3)underset(|)N-CH_(3)`

Answer

To determine which of the following compounds is a tertiary amine, we need to understand the definitions of primary, secondary, and tertiary amines:

1. **Primary Amine**: A primary amine has one nitrogen atom attached to two hydrogen atoms and one alkyl or aryl group. The general structure is R-NH2, where R is an alkyl or aryl group.

2. **Secondary Amine**: A secondary amine has one nitrogen atom attached to one hydrogen atom and two alkyl or aryl groups. The general structure is R2-NH, where R can be either an alkyl or aryl group.

3. **Tertiary Amine**: A tertiary amine has one nitrogen atom attached to three alkyl or aryl groups and does not have any hydrogen atoms attached to the nitrogen. The general structure is R3-N, where R can be either an alkyl or aryl group.

Now, let's analyze the compounds given in the question:

1. **First Compound**: Contains two hydrogen atoms attached to nitrogen and one alkyl or aryl group. This qualifies as a primary amine.

2. **Second Compound**: Contains one hydrogen atom attached to nitrogen and two alkyl or aryl groups. This qualifies as a secondary amine.

3. **Third Compound**: Contains two aryl groups and one hydrogen atom attached to nitrogen. This qualifies as a secondary amine as well because it still has one hydrogen atom.

4. **Fourth Compound**: Contains three alkyl groups attached to nitrogen and no hydrogen atoms. This qualifies as a tertiary amine.

Based on this analysis, the correct answer is that the fourth option is a tertiary amine.

### Step-by-Step Solution:
1. **Identify the types of amines**: Understand the definitions of primary, secondary, and tertiary amines.
2. **Analyze the first compound**: Check for the number of hydrogen atoms and alkyl/aryl groups. It has 2 hydrogens and 1 alkyl/aryl group, making it a primary amine.
3. **Analyze the second compound**: It has 1 hydrogen and 2 alkyl/aryl groups, making it a secondary amine.
4. **Analyze the third compound**: It has 2 aryl groups and 1 hydrogen, which also makes it a secondary amine.
5. **Analyze the fourth compound**: It has 3 alkyl groups and no hydrogen atoms, making it a tertiary amine.
6. **Conclusion**: The fourth option is the correct answer as it is the only tertiary amine.