Lactic acid `CH_3-oversetoverset(OH)(|)CH-oversetoverset(O)(||)C-OH` can be prepared by acid hydrolysis of reaction product of

Options

A. Ethanal with HCN/KCN mixture
B. Ethanol with `PCl_5` followed by KCN
C. Propanal with KCN, in presence of `NH_4Cl`
D. `CrO_3`/acetic acid and isopropyl alcohol

Explanation

To solve the question regarding the preparation of lactic acid (CH₃CHOHCOOH) through acid hydrolysis of a reaction product, we will analyze the options provided and identify the correct precursor compound.

### Step-by-Step Solution:

1. **Identify the Structure of Lactic Acid**:
- Lactic acid has the molecular formula CH₃CHOHCOOH. It consists of a hydroxyl group (-OH) and a carboxylic acid group (-COOH).

2. **Evaluate the Options**:
- We need to evaluate the four options given to determine which compound can yield lactic acid upon acid hydrolysis.

3. **Option A: Ethanol (C₂H₅OH)**:
- Ethanol can react with HCN in the presence of a catalyst (like KCN) to form an intermediate product.
- The reaction would yield a compound that can be further hydrolyzed to produce lactic acid.

4. **Option B: Ethanol with PCl₅**:
- When ethanol reacts with PCl₅, it forms an alkyl chloride. This compound does not lead to lactic acid upon hydrolysis.

5. **Option C: Propanol (C₃H₇OH)**:
- Propanol can also react with HCN to form a cyanohydrin, which can be hydrolyzed. However, this does not lead to the formation of lactic acid.

6. **Option D: Acetic Acid (CH₃COOH)**:
- Acetic acid reacts with isopropyl alcohol in an esterification reaction, which does not yield lactic acid.

7. **Conclusion**:
- From the analysis, the only viable option that leads to the formation of lactic acid through acid hydrolysis is **Option A: Ethanol**.

### Final Answer:
Lactic acid can be prepared by acid hydrolysis of the reaction product of **Ethanol (C₂H₅OH)**.