Which one of the following constitutes natural silk ?

Options

A. Nitrogen
B. Magnesium
C. Potassium
D. Phosphorus

Answer

To answer the question "Which one of the following constitutes natural silk?", we can follow these steps:

### Step 1: Understand what natural silk is
Natural silk is a protein fiber produced by certain insects, primarily the silkworm. The two main proteins that make up silk are sericin and fibroin.

### Step 2: Identify the components of silk
- **Sericin**: This is a protein that surrounds the fibroin fibers and is composed of amino acids, which contain nitrogen.
- **Fibroin**: This is the structural center of the silk fiber and is also primarily made up of amino acids, which again contain nitrogen.

### Step 3: Analyze the composition of these proteins
Both sericin and fibroin are rich in amino acids, and amino acids are organic compounds that contain nitrogen as a fundamental element.

### Step 4: Determine the answer
Given that both sericin and fibroin contain nitrogen, we can conclude that nitrogen is a key component of natural silk.

### Conclusion
Thus, the correct answer to the question "Which one of the following constitutes natural silk?" is **Nitrogen**.

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