Isobutyraldehyde on reaction with formaldehyde and `K_2CO_3`, gives compound 'A'. Compound "A' reacts with KCN and yields compound 'B', which on hydrolysis gives a stable compound 'C'. The compound 'C' is

Options

A. `HO-CH_2-overset(CH_3)overset(|)underset(CH_3)underset(|)(C)-underset(OH)underset(|)(CH)-COOH`
B. `HO-CH_2CH_2-underset(CH_3)underset(|)(CH)-underset(OH)underset(|)(CH)-COOH`
C.
D.

Explanation

To solve the problem step by step, we will analyze the reactions involving isobutyraldehyde, formaldehyde, K2CO3, KCN, and the hydrolysis process to find the stable compound 'C'.

### Step 1: Reaction of Isobutyraldehyde with Formaldehyde
Isobutyraldehyde (CH3)2C=CHOH reacts with formaldehyde (HCHO) in the presence of K2CO3 (a base). This reaction is a typical example of an aldol condensation, where two aldehydes react to form a β-hydroxy aldehyde.

The reaction can be represented as follows:
- Isobutyraldehyde + Formaldehyde → Compound A

The structure of Compound A will be:
- Compound A: (CH3)2C(OH)CH2CHO

### Step 2: Reaction of Compound A with KCN
Next, Compound A reacts with KCN (potassium cyanide). This reaction typically involves nucleophilic addition of the cyanide ion (CN-) to the carbonyl group of Compound A, leading to the formation of a cyanohydrin.

The reaction can be represented as follows:
- Compound A + KCN → Compound B

The structure of Compound B will be:
- Compound B: (CH3)2C(OH)CH(CN)OH

### Step 3: Hydrolysis of Compound B
Now, Compound B undergoes hydrolysis. In this step, the cyanide group (CN) is converted to a carboxylic acid (COOH) through hydrolysis.

The reaction can be represented as follows:
- Compound B + H2O → Compound C

The structure of Compound C will be:
- Compound C: (CH3)2C(OH)COOH

### Step 4: Stability of Compound C
Compound C is stable due to the presence of the carboxylic acid group and the hydroxyl group, which can form intramolecular hydrogen bonds, contributing to its stability.

### Final Answer
The stable compound 'C' is:
- Compound C: 2-Hydroxy-4-methylpentanoic acid (or 2-hydroxy-3-methylbutanoic acid)

---