`Cl_3-underset((X))-=-Hunderset(D_2+P-2catalyst)rarr(A)overset(HCl)rarr(B)`
Compounds (A) and (B) are:

Options

A.
B.
C.
D.

Explanation

To solve the problem, we need to identify the compounds A and B based on the given reactions. Let's break down the steps systematically.

### Step 1: Identify Compound X
The question states that we start with a compound represented as Cl₃-X-H, where X is a carbon atom with a triple bond. This means that X is likely a terminal alkyne with three chlorine atoms attached to it.

**Hint:** Look for the structure of a terminal alkyne with three chlorine substituents.

### Step 2: Reaction with D₂ and P₂ Catalyst
When compound X reacts with D₂ in the presence of a P₂ catalyst, it undergoes hydrogenation. This reaction will add hydrogen atoms across the triple bond. Since the reaction is a syn addition, both hydrogen atoms will add to the same side of the triple bond.

**Hint:** Remember that syn addition means both substituents add to the same side of the double bond.

### Step 3: Structure of Compound A
After the syn addition of D₂, compound A will have two hydrogen atoms added to the triple bond, converting it into a double bond. The structure of compound A can be represented as Cl₃C-CH=DH, where D represents the deuterium atoms added.

**Hint:** Visualize the addition of hydrogen atoms to the triple bond and how it affects the overall structure.

### Step 4: Reaction with HCl
Next, compound A reacts with HCl. In this reaction, HCl will add across the double bond. The hydrogen from HCl will add to the carbon with fewer substituents (following Markovnikov's rule), while the chlorine will add to the other carbon.

**Hint:** Apply Markovnikov's rule to determine where the H and Cl will add.

### Step 5: Structure of Compound B
After the addition of HCl to compound A, compound B will be formed. The structure can be represented as Cl₃C-CH₂Cl, where one chlorine atom remains attached to the first carbon, and the other chlorine atom is now attached to the second carbon.

**Hint:** Ensure to account for the addition of H and Cl correctly based on the structure of compound A.

### Final Structures
- **Compound A:** Cl₃C-CH=DH
- **Compound B:** Cl₃C-CH₂Cl

### Conclusion
Based on the above steps, we have identified the compounds A and B as follows:
- **Compound A:** Cl₃C-CH=DH
- **Compound B:** Cl₃C-CH₂Cl