A feature absent in annelids in

Options

A. Clitellum
B. Pseudocoelom
C. Metameric segmentation
D. Nephridia

Answer

To determine a feature that is absent in annelids, we can analyze the given options one by one.

### Step-by-Step Solution:

1. **Understand Annelids**: Annelids are a phylum of segmented worms, which includes organisms like earthworms and leeches. They are characterized by their segmented body structure, where the body is divided into multiple segments, each containing similar sets of organs.

2. **Evaluate the Options**:
- **Option 1: Clitellum**: The clitellum is a thickened, glandular section of the body wall in certain annelids, particularly in earthworms. It plays a crucial role in reproduction by forming a cocoon for eggs. Since the clitellum is present in many annelids, this option is incorrect.

- **Option 2: Pseudocoelom**: A pseudocoelom is a body cavity that is not completely lined by mesoderm. It is found in organisms like roundworms (phylum Nematoda). Annelids, on the other hand, possess a true coelom, which is a body cavity fully lined by mesoderm. Therefore, pseudocoelom is indeed absent in annelids, making this option correct.

- **Option 3: Metameric Segmentation**: This is a defining feature of annelids, where the body is segmented. Since segmentation is a characteristic of annelids, this option is also incorrect.

- **Option 4: Nephridia**: Nephridia are the excretory organs found in annelids, responsible for the removal of waste. Since they are present in annelids, this option is incorrect as well.

3. **Conclusion**: After evaluating all the options, the feature that is absent in annelids is **pseudocoelom**.

### Final Answer:
The feature absent in annelids is **pseudocoelom**.

---