p-cresol reacts with chloroform in alkaline medium to give the compound A which adds hydrogen cyanide to form, the compound B. the latter on acidic hydrolysis gives chiral caboxylic acid. The structure of the carboxylic acid is

Options

A.
B.
C.
D.

Explanation

To solve the problem step-by-step, we will follow the reactions mentioned in the question involving p-cresol, chloroform, and hydrogen cyanide.

### Step 1: Identify the structure of p-cresol
p-Cresol is a methylphenol with the following structure:
- It has a hydroxyl group (-OH) and a methyl group (-CH3) attached to a benzene ring at the para position.

**Structure of p-cresol:**
```
OH
|
CH3-C6H4
```

### Step 2: Reaction of p-cresol with chloroform in alkaline medium
When p-cresol reacts with chloroform (CHCl3) in the presence of a strong base like KOH, it undergoes the Reimer-Tiemann reaction. This reaction converts phenols into ortho- and para-hydroxybenzaldehydes.

**Product A:**
In this case, the para position will be favored, leading to the formation of p-hydroxybenzaldehyde (also known as salicylaldehyde).

**Structure of Product A:**
```
OH
|
CH3-C6H4-CHO
```

### Step 3: Addition of hydrogen cyanide to Product A
Next, we add hydrogen cyanide (HCN) to the aldehyde (Product A). The cyanide ion (CN-) will attack the carbonyl carbon of the aldehyde, leading to the formation of a cyanohydrin.

**Product B:**
The resulting compound will have both a hydroxyl group and a cyanide group.

**Structure of Product B:**
```
OH
|
CH3-C6H4-CH(OH)-CN
```

### Step 4: Acidic hydrolysis of Product B
When Product B undergoes acidic hydrolysis, the cyanide group (-CN) is converted into a carboxylic acid (-COOH). This reaction also leads to the formation of a chiral center.

**Final Product:**
The final product after hydrolysis will be a chiral carboxylic acid.

**Structure of the chiral carboxylic acid:**
```
OH
|
CH3-C6H4-COOH
```

### Conclusion
The structure of the chiral carboxylic acid formed is:
```
OH
|
CH3-C6H4-COOH
```