`|{:(Column I,Column 2,Column 3),((I)"Toluene",(i)NaOH//Br_(2),(P)"Condensation"),((II)"Acetophenone",(ii)Br_(2)//hv,(Q)"Carboxylation"),((III)"Benzaldehyde",(iii)(CH_(3)CO)_(2)O //CH_(3)COOK,(R)"Substitution"),((IV)"Phenol",(iv)NaOH//CO_(2),(S)"Haloform"):}|`
For the synthesis of benzoic acid, the only CORRECT combination is

Options

A. (II) (i) (S)
B. (I) (iv) (Q)
C. (IV) (ii) (P)
D. (III) (iv) (R )

Explanation

To solve the question regarding the synthesis of benzoic acid using the combinations from the provided columns, we need to analyze each option step by step.

### Step 1: Analyze Column I
- **Toluene**: Toluene can undergo bromination in the presence of NaOH and Br2, leading to a substitution reaction.
- **Acetophenone**: Acetophenone can undergo a haloform reaction in the presence of NaOH and Br2.
- **Benzaldehyde**: Benzaldehyde can undergo condensation reactions, particularly Perkin condensation.
- **Phenol**: Phenol can undergo carboxylation in the presence of NaOH and CO2.

### Step 2: Analyze Column II
- **(i) NaOH//Br2**: This combination is suitable for the haloform reaction.
- **(ii) Br2//hv**: This combination is typically used for free radical bromination, which is not directly relevant for benzoic acid synthesis.
- **(iii) (CH3CO)2O // CH3COOK**: This is indicative of a condensation reaction, which is relevant for benzaldehyde.
- **(iv) NaOH//CO2**: This combination is used for carboxylation reactions, which can produce benzoic acid from phenol.

### Step 3: Analyze Column III
- **(P) Condensation**: This matches with benzaldehyde.
- **(Q) Carboxylation**: This matches with phenol.
- **(R) Substitution**: This matches with toluene.
- **(S) Haloform**: This matches with acetophenone.

### Step 4: Match Combinations
Now we need to find the correct combination that leads to the synthesis of benzoic acid:
1. **Toluene + NaOH//Br2 + Substitution**: This does not lead to benzoic acid.
2. **Acetophenone + Br2//hv + Haloform**: This does not lead to benzoic acid.
3. **Benzaldehyde + (CH3CO)2O // CH3COOK + Condensation**: This does not lead to benzoic acid.
4. **Phenol + NaOH//CO2 + Carboxylation**: This leads to the formation of benzoic acid.

### Conclusion
The only correct combination for the synthesis of benzoic acid is:
- **Phenol + NaOH//CO2 + Carboxylation**.

Thus, the answer is **Option 4**.