The only phylum bearing pseudocoelom is

Options

A. Annelida
B. Porifera
C. Aschelminthes
D. Platyhelminthes

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question:** The question asks for the only phylum that has a pseudocoelom. We need to identify which of the given options possesses this characteristic.

2. **Defining Coelom:** A coelom is a fluid-filled body cavity that is completely lined by mesoderm tissue. There are three types of body cavities:
- **Acoelomate:** Organisms that lack a coelom.
- **Pseudocoelomate:** Organisms that have a pseudocoelom, which is a body cavity not entirely lined by mesoderm.
- **Coelomate:** Organisms that have a true coelom, which is completely lined by mesoderm.

3. **Analyzing the Options:**
- **Option A - Annelida:** This phylum has a true coelom, so it does not qualify.
- **Option B - Porifera:** Members of this phylum are acoelomate, meaning they do not have a coelom.
- **Option C - Platyhelminthes:** This phylum also has a true coelom and is classified as acoelomate.
- **Option D - Aschelminthes (Nematoda):** This phylum is known for having a pseudocoelom.

4. **Conclusion:** Among the options provided, the only phylum that bears a pseudocoelom is Aschelminthes (Nematoda).

5. **Final Answer:** The answer is **Aschelminthes**.

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