Choose the correct option

Options

A. A closed circular system - Annelida
B. Nereis - Aquatic, Dioecious
C. Pheretima and Leech - Monoecious
D. All

Answer

To solve the question regarding the characteristics of the phylum Annelida, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding the Phylum Annelida**:
- Annelida is a phylum that includes segmented worms such as earthworms and leeches. They are characterized by their segmented bodies.

2. **Characteristics of Annelida**:
- **Triploblastic**: Annelids are triploblastic, meaning they have three germ layers: ectoderm, mesoderm, and endoderm.
- **True Coelomate**: They possess a true coelom, which is a body cavity lined by mesoderm.
- **Complete Digestive Tract**: Annelids have a complete digestive system, which means they have a mouth and an anus.
- **Excretory Organs**: They have specialized excretory organs called nephridia.
- **Presence of Parapodia**: Many annelids have parapodia, which are lateral extensions used for locomotion and respiration.
- **Metamerism**: Annelids exhibit metamerism, meaning their bodies are divided into segments.
- **Closed Circulatory System**: Annelids have a closed circulatory system, where blood is contained within vessels.

3. **Examining the Options**:
- **Option 1**: "Annelida has a closed circulatory system."
- This is **correct** as many annelids, such as earthworms, have a closed circulatory system.
- **Option 2**: "Neris is Aquatic and Dioecious."
- This is **correct**. Neris, a type of polychaete worm, is aquatic and has separate sexes (dioecious).
- **Option 3**: "Ferretema and Leech is Monoecious."
- This is **correct**. Both Ferretema (a type of earthworm) and leeches are monoecious, meaning they have both male and female reproductive organs in the same individual.
- **Option 4**: "All options are correct."
- Since all the previous options are correct, this option is also **correct**.

4. **Conclusion**:
- After analyzing all the options, we conclude that all statements regarding Annelida are correct. Therefore, the correct answer is Option 4.

### Final Answer:
**Option 4: All options are correct.**