Assertion : Phenol is a weak acid than ethanol.
Reason : Groups with +M effect and -I effect decrease acidity at m-position .

Options

A. If both the assertion and reason are true and reason is correct explanation of the assertion .
B. If both the assertion and reason are true but reason is not a correct explanation of the assertion .
C. If the assertion is true but the reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Phenol is a weaker acid than ethanol."
- To evaluate this, we need to consider the acidity of both compounds. Phenol (C6H5OH) can donate a proton (H+) to form the phenoxide ion (C6H5O-), which is resonance-stabilized. Ethanol (C2H5OH), on the other hand, can donate a proton to form the ethoxide ion (C2H5O-), which is not resonance-stabilized.
- Since the phenoxide ion is more stable due to resonance, phenol is actually a stronger acid than ethanol.

2. **Understanding the Reason**:
- The reason states that "Groups with +M effect and -I effect decrease acidity at m-position."
- The +M (mesomeric) effect refers to the ability of certain groups to donate electron density through resonance, while the -I (inductive) effect refers to the withdrawal of electron density through sigma bonds.
- The statement about the m-position is misleading because groups with +M effect typically increase acidity by stabilizing the negative charge on the conjugate base, while -I effect groups can decrease acidity by destabilizing the conjugate base. However, the assertion does not relate directly to the reason provided.

3. **Conclusion**:
- Since the assertion is false (phenol is a stronger acid than ethanol) and the reason is also false (it does not correctly explain the assertion), we conclude that both the assertion and the reason are incorrect.

### Final Answer:
Both assertion and reason are false.