Aschelminthes differs from other phyla in having

Options

A. Bilateral symmetry
B. Cylindrical body
C. Pseudocoelom
D. Parasitic mode

Answer

### Step-by-Step Solution:

1. **Identify the Phylum**: The question pertains to the phylum Aschelminthes, also known as Nemathelminthes, which includes organisms commonly referred to as roundworms.

2. **Understand the Characteristics**: Aschelminthes have several distinctive features that differentiate them from other phyla. Key characteristics include:
- **Cylindrical Body Shape**: Their bodies are elongated and cylindrical.
- **Bilateral Symmetry**: They exhibit bilateral symmetry, which is common in many other animal phyla as well.
- **Presence of Pseudocoelom**: They possess a pseudocoelom, which is a body cavity that is not completely lined by mesoderm.
- **Lack of Locomotory Structures**: They do not have specialized structures for locomotion.

3. **Evaluate the Options**:
- **Option A: Bilateral Symmetry**: This is incorrect as many other phyla, such as Arthropoda, also exhibit bilateral symmetry.
- **Option B: Cylindrical Body**: This is also incorrect because cylindrical body shapes can be found in other phyla as well.
- **Option C: Pseudocoelom**: This is the correct answer as the presence of a pseudocoelom is a unique characteristic of Aschelminthes.
- **Option D: Parasitic Mode**: This is incorrect because parasitism is found in various other phyla, including flatworms.

4. **Conclusion**: The distinguishing feature of Aschelminthes compared to other phyla is the presence of a pseudocoelom. Therefore, the correct answer is **Pseudocoelom**.

### Final Answer:
Aschelminthes differs from other phyla in having a **pseudocoelom**.

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