Assertion (A): Benzoic acid does not undergo Friedel-craft's reaction.
Reaction (R): The carboxyl group is activating and undergo electrophilic substitution reaction.

Options

A. Both A and Rare true and R is the correct explanation of A
B. Both A and R are true but R is NOT the correct explanation of A
C. A is true but R is false
D. A is false and R is true

Explanation

To analyze the assertion and reaction provided in the question, we will break down the concepts of Friedel-Crafts reactions, the nature of the carboxyl group, and the behavior of benzoic acid in this context.

### Step-by-Step Solution:

1. **Understanding Friedel-Crafts Reaction**:
- Friedel-Crafts reactions are electrophilic aromatic substitution reactions where an alkyl or acyl group is introduced into an aromatic ring. This reaction typically requires a Lewis acid catalyst, such as AlCl3, to generate a more reactive electrophile.

**Hint**: Remember that Friedel-Crafts reactions involve the substitution of hydrogen atoms on an aromatic ring with alkyl or acyl groups.

2. **Analyzing Benzoic Acid**:
- Benzoic acid (C6H5COOH) contains a carboxyl group (-COOH) attached to a benzene ring. The carboxyl group is known to be a deactivating group due to its electron-withdrawing nature.

**Hint**: Identify the functional groups in benzoic acid and their effects on the aromatic ring.

3. **Effect of the Carboxyl Group**:
- The carboxyl group (-COOH) is a strong electron-withdrawing group due to its -I (inductive) and -M (mesomeric) effects. This decreases the electron density on the benzene ring, making it less reactive towards electrophiles.

**Hint**: Consider how electron-withdrawing groups influence the reactivity of the aromatic ring in electrophilic substitution reactions.

4. **Friedel-Crafts Reaction with Benzoic Acid**:
- Due to the deactivating nature of the carboxyl group, benzoic acid does not undergo Friedel-Crafts reactions. The presence of the -COOH group makes it difficult for the electrophile (carbocation) to attack the benzene ring.

**Hint**: Recall that for a successful Friedel-Crafts reaction, the aromatic compound should be activated, which is not the case for benzoic acid.

5. **Conclusion on Assertion and Reaction**:
- Assertion (A): "Benzoic acid does not undergo Friedel-Crafts reaction" is **True**.
- Reaction (R): "The carboxyl group is activating and undergoes electrophilic substitution reaction" is **False** because the carboxyl group is deactivating.

**Hint**: Differentiate between activating and deactivating groups and their impact on electrophilic substitution.

### Final Answer:
- The assertion is true, but the reason is false. Benzoic acid does not undergo Friedel-Crafts reactions due to the deactivating effect of the carboxyl group.