Primary `(1^@)` amine group is formed in :

Options

A.
B.
C.
D.

Explanation

To determine which reactions produce primary amine groups, we will analyze each given option step by step.

### Step 1: Analyze the first reaction
- The first reaction involves a nitro compound (NO2) reacting with N-E-H-S (which is likely a reducing agent).
- When one equivalent of N-E-H-S is used, the nitro group (NO2) is reduced to an amine group (NH2).
- The resulting product has the nitrogen atom connected to only one carbon atom and has two hydrogen atoms attached to it.

**Conclusion for Step 1**: This product is a primary amine.

### Step 2: Analyze the second reaction
- The second reaction involves an amine (NH2) reacting with a carbonyl compound (C=O) in the presence of Br2 and KOH.
- The product formed from this reaction also has the nitrogen atom connected to only one carbon atom, with two hydrogen atoms attached.

**Conclusion for Step 2**: This product is also a primary amine.

### Step 3: Analyze the third reaction
- The third reaction involves chlorobenzene reacting with CH2NH2, Cu2O, and heat.
- The product formed has the nitrogen atom connected to two carbon atoms (one from the chlorobenzene and one from CH2), indicating that this is a secondary amine.

**Conclusion for Step 3**: This product is not a primary amine.

### Step 4: Analyze the fourth reaction
- The fourth reaction involves benzene diazonium salt (N2Cl) reacting with Zn/HCl.
- The product formed is aniline (NH2 connected to a benzene ring), which has the nitrogen atom connected to only one carbon atom (the benzene ring) and has two hydrogen atoms attached.

**Conclusion for Step 4**: This product is a primary amine.

### Final Conclusion
- From the analysis, the reactions that produce primary amines are:
- Reaction 1: Produces a primary amine.
- Reaction 2: Produces a primary amine.
- Reaction 3: Does not produce a primary amine (produces a secondary amine).
- Reaction 4: Produces a primary amine.

Thus, the correct options that yield primary amines are A, B, and D.