The peptide that gives positive ceric ammonium nitrate and carbylamines tests is:

Options

A. Lys - Asp
B. Ser – Lys
C. Asp - Gln
D. Gln - Asp

Explanation

To determine which peptide gives positive tests for both ceric ammonium nitrate and carbylamines, we need to analyze the functional groups present in the given peptides. The tests are based on specific functional groups:

1. **Ceric Ammonium Nitrate Test**: This test is positive for compounds containing hydroxyl (-OH) groups.
2. **Carbylamines Test**: This test is positive for compounds containing primary amines (-NH2 groups).

Let's analyze each peptide provided in the options:

### Peptides Given:
1. **LYS-ASP** (Lysine-Aspartic Acid)
2. **SER-LYS** (Serine-Lysine)
3. **ASP-GLN** (Aspartic Acid-Glutamine)
4. **GLN-ASP** (Glutamine-Aspartic Acid)

### Step-by-Step Analysis:

**Step 1: Analyze LYS-ASP**
- **Lysine (LYS)** has an -NH2 group (primary amine).
- **Aspartic Acid (ASP)** does not have an -OH group.
- **Conclusion**: LYS-ASP gives a positive carbylamines test but not a positive ceric ammonium nitrate test.

**Step 2: Analyze SER-LYS**
- **Serine (SER)** has an -OH group (hydroxyl).
- **Lysine (LYS)** has an -NH2 group (primary amine).
- **Conclusion**: SER-LYS gives positive tests for both ceric ammonium nitrate and carbylamines.

**Step 3: Analyze ASP-GLN**
- **Aspartic Acid (ASP)** does not have an -OH group.
- **Glutamine (GLN)** does not have an -OH group.
- **Conclusion**: ASP-GLN does not give positive tests for either.

**Step 4: Analyze GLN-ASP**
- **Glutamine (GLN)** does not have an -OH group.
- **Aspartic Acid (ASP)** does not have an -OH group.
- **Conclusion**: GLN-ASP does not give positive tests for either.

### Final Conclusion:
The peptide that gives positive ceric ammonium nitrate and carbylamines tests is **SER-LYS**.

### Answer:
**SER-LYS**