Which of the following is pseudoceolomate

Options

A. Hydra
B. Periplaneta
C. Ascaris
D. Pheretima

Answer

To determine which of the following organisms is a pseudocoelomate, we will analyze each option based on their body cavity structure.

### Step-by-Step Solution:

1. **Understanding Pseudocoelomate**:
- A pseudocoelomate is an organism that has a body cavity (the pseudocoelom) that is not completely lined by mesoderm. This cavity is located between the endoderm and the mesoderm.

2. **Analyzing the Options**:
- **Option 1: Hydra**:
- Hydra is an example of an acoelomate organism, meaning it lacks a body cavity altogether. Therefore, this option is incorrect.

- **Option 2: Pariplaneta (Cockroach)**:
- In Pariplaneta, the body cavity is a true coelom, which is formed by the splitting of the mesoderm. Thus, this organism is not a pseudocoelomate. This option is also incorrect.

- **Option 3: Ascaris**:
- Ascaris is a nematode and is classified as a pseudocoelomate. The body cavity in Ascaris is a pseudocoelom, which is situated between the endoderm and mesoderm. This option is correct.

- **Option 4: Pharytema (Earthworm)**:
- Pharytema, or earthworms, possess a true coelom that is completely lined by mesoderm. Therefore, this option is incorrect as well.

3. **Conclusion**:
- The only organism among the options that is a pseudocoelomate is **Ascaris**.

### Final Answer:
- The correct answer is **Option 3: Ascaris**.