The most basic compound in the following is

Options

A. `NH_(3)`
B. `CH_(3)NH_(2)`
C. `NH(CH_(3))_(2)`
D. `N(CH_(3))_(2)`

Explanation

To determine the most basic compound among the given options, we need to analyze the basicity of each compound based on the presence of nitrogen and the influence of alkyl groups (like CH3) on the lone pair of electrons on nitrogen.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- The compounds given are:
1. Ammonia (NH3)
2. Methylamine (CH3NH2)
3. Dimethylamine (CH3)2NH
4. Trimethylamine (CH3)3N

2. **Understand Basicity**:
- Basicity is determined by the ability of a compound to donate a lone pair of electrons. The more easily a lone pair can be donated, the more basic the compound is.

3. **Effect of Alkyl Groups**:
- Alkyl groups (like CH3) are electron-donating groups (through +I effect). They increase the electron density on the nitrogen atom, making it more likely to donate its lone pair.

4. **Analyze Each Compound**:
- **Ammonia (NH3)**: Has no alkyl groups. The lone pair is available for donation, but the basicity is relatively low.
- **Methylamine (CH3NH2)**: One CH3 group increases the electron density on nitrogen, making it more basic than ammonia.
- **Dimethylamine ((CH3)2NH)**: Two CH3 groups further increase the electron density, making it more basic than methylamine.
- **Trimethylamine ((CH3)3N)**: Three CH3 groups provide the highest electron density on nitrogen, making it the most basic of all.

5. **Conclusion**:
- Among the four compounds, trimethylamine ((CH3)3N) has the highest basicity due to the presence of three electron-donating methyl groups, which enhance the ability of nitrogen to donate its lone pair.

### Final Answer:
The most basic compound is **Trimethylamine ((CH3)3N)**.