`+m` and `+I` both effects are shown by:

Options

A. `-overset(..)underset(..)(O)H`
B. `-ddot(N)HCH_(3)`
C. `-O^(Theta)`
D. `-C(CH_(3))_(3)`

Answer

To solve the question regarding which compounds exhibit both +M (mesomeric effect) and +I (inductive effect), we will analyze the effects of different functional groups in organic compounds.

### Step-by-Step Solution:

1. **Understanding +M and +I Effects**:
- **+M Effect**: This is the mesomeric effect, which involves the delocalization of electrons through resonance. It typically occurs in compounds with lone pairs on electronegative atoms (like O, N) that can donate electrons to the π system.
- **+I Effect**: This is the inductive effect, which refers to the permanent polarization of a bond due to the electronegativity of atoms. Electron-donating groups (like alkyl groups) exhibit a +I effect.

2. **Analyzing Functional Groups**:
- **Oxygen (O)**: Oxygen can show a +M effect due to its lone pairs but can also exhibit a -I effect due to its electronegativity. Therefore, it does not contribute to both +M and +I.
- **Nitrogen (N)**: Nitrogen has a lone pair that can participate in resonance, thus showing a +M effect. However, it is also electronegative and can exhibit a -I effect, but it does not contribute to a +I effect.
- **Alkyl Groups (e.g., CH3)**: Alkyl groups can exhibit a +I effect as they are electron-donating through inductive effects but do not have lone pairs to show a +M effect.

3. **Identifying the Correct Compound**:
- We need to find a compound that has both a +M effect and a +I effect.
- A compound that has both an alkyl group (for +I) and a functional group with a lone pair (for +M) would be ideal.

4. **Conclusion**:
- After analyzing the effects of different groups, the compound that shows both +M and +I effects is likely one that contains both an electron-donating group (like an alkyl group) and a functional group capable of resonance (like an amine or ether).

Thus, the correct answer to the question is the compound that has both +M and +I effects, which is typically represented as the one with a nitrogen atom bonded to an alkyl group.

### Final Answer:
The compound that exhibits both +M and +I effects is the one containing a nitrogen atom with a lone pair and an alkyl group.