Chaeta of Pheretima is about

Options

A. `0*025` mm long
B. `0*25` mm long
C. `0*5` mm long
D. `2*5` mm long

Answer

To solve the question regarding the chaeta of Pheretima, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Organism**:
- Pheretima is a genus of earthworms, which belong to the phylum Annelida.

2. **Understand the Structure**:
- Chaetae (or setae) are chitinous bristles found on the body of annelids, including earthworms. They play a crucial role in locomotion.

3. **Determine the Size of Chaeta**:
- The question asks for the size of the chaeta in Pheretima. Based on biological studies, the diameter of the chaeta in Pheretima is approximately 0.25 mm.

4. **Evaluate the Options**:
- The options provided are:
- a) 0.025 mm
- b) 0.25 mm
- c) 0.5 mm
- d) 2.5 mm
- From the information gathered, the correct size of the chaeta is 0.25 mm.

5. **Select the Correct Option**:
- Therefore, the correct answer is option b) 0.25 mm.

### Final Answer:
The chaeta of Pheretima is about **0.25 mm long**.