Multinucleate decomposer organism is

Options

A. Physarum
B. Pelomyxa
C. Arcella
D. Dictyostelium.

Answer

### Step-by-Step Solution

1. **Understanding the Question**: The question asks for a multinucleate decomposer organism. Decomposers are organisms that break down dead organic material, and in the context of the question, we are looking for a member of the kingdom Protista.

2. **Identifying Characteristics of Decomposers**: Decomposers in the kingdom Protista often include slime molds. These organisms can exist in different forms, including a multinucleate form.

3. **Exploring the Options**: The options given are:
- Physarum
- Pleomyxa
- Arcella
- Dictyostelium

4. **Analyzing Each Option**:
- **Physarum**: This is a slime mold that exists in a multinucleated form known as plasmodium. It is a well-known decomposer.
- **Pleomyxa**: This organism belongs to the family Amoebozoa but does not typically exhibit a multinucleate form as a decomposer.
- **Arcella**: This organism has a single nucleus and is not a decomposer in the same sense as slime molds.
- **Dictyostelium**: This is a cellular slime mold that primarily exists in a single nucleus form and is not classified as a multinucleate organism.

5. **Conclusion**: Based on the analysis, the correct answer is **Physarum**. It is a multinucleate decomposer organism that fits the criteria outlined in the question.

### Final Answer
The multinucleate decomposer organism is **Physarum**.

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