Pick out the odd one on the basis of phylum:-

Options

A. Nereis
B. Pheretima
C. Hirudinaria
D. Wuchereria

Answer

To solve the question of identifying the odd one out based on phylum, we will analyze each option provided:

1. **Neeris**: Neeris belongs to the phylum Annelida. This phylum is characterized by segmented worms, and Neeris is a type of polychaete worm.

2. **Faratima**: Faratima, also known as the earthworm, is also part of the phylum Annelida. Like Neeris, it is segmented and shares similar characteristics with other annelids.

3. **Herodineria**: Herodineria refers to a type of leech, which is again a member of the phylum Annelida. Leeches are segmented worms that are known for their blood-sucking behavior.

4. **Hirudinea**: This term refers to the class of leeches within the phylum Annelida. However, it is not an individual organism but rather a classification of organisms that includes various types of leeches.

Now, we can summarize the findings:

- Neeris, Faratima, and Herodineria are all specific organisms within the phylum Annelida.
- Hirudinea, while related, is a class name rather than a specific organism.

**Conclusion**: The odd one out is **Hirudinea**, as it refers to a class rather than a specific organism like the others.

### Step-by-Step Solution:
1. Identify the phylum of Neeris (Annelida).
2. Identify the phylum of Faratima (Annelida).
3. Identify the phylum of Herodineria (Annelida).
4. Identify the classification of Hirudinea (class within Annelida).
5. Compare the options and conclude that Hirudinea is the odd one out since it is a class, not a specific organism.