Retting of fibres is brought about by the activity of :

Options

A. viruses
B. fungi
C. bacteria
D. mycorrhiza

Answer

To solve the question "Retting of fibres is brought about by the activity of:", we will analyze the process of retting and identify the organism responsible for it.

### Step-by-Step Solution:

1. **Understanding Retting**:
- Retting is a process used to separate the fibers from the stems of plants. It involves the breakdown of pectin, a substance that binds the fibers to the stem.

2. **Identifying the Role of Microorganisms**:
- The retting process is facilitated by microorganisms that produce enzymes capable of degrading pectin.

3. **Recognizing the Key Microorganism**:
- Among the various microorganisms, bacteria play a significant role in the retting process. Specifically, the bacterium *Clostridium* is known for its ability to secrete the enzyme pectinase.

4. **Function of Pectinase**:
- Pectinase is an enzyme that breaks down pectin, leading to the dissolution of the fibers from the plant stem. This is crucial for the retting process.

5. **Conclusion**:
- Therefore, the activity responsible for the retting of fibers is primarily due to the action of *Clostridium* bacteria, which secrete pectinase to degrade pectin.

### Final Answer:
Retting of fibres is brought about by the activity of **Bacteria** (specifically *Clostridium*).

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