Slime molds are placed under myxomycetes and are characterized by the presence of different morphology at different life stages. The vegetative stage of cellular slime molds is a haploid amoeboid cell and is known as pseudoplasmodium. Thus, the correct answer is D. 

Pseudoplasmodium In cellular slime moulds, a plasmodium-like structure formed by the aggregation of many separate amoeboid cells.so answer would be (d).

Pseudoplasmodium is characteristic of Cellular slime molds.

Explanation:
Cellular slime molds, also known as Dictyostelids, are a group of eukaryotic microorganisms that exhibit a unique life cycle. During certain stages of their life cycle, cellular slime molds form a multicellular structure called a pseudoplasmodium or slug.

Life Cycle of Cellular Slime Molds:
1. Individual Amoeboid Cells: The life cycle of cellular slime molds begins with individual amoeboid cells. These cells live independently and feed on bacteria and other organic matter in the environment.

2. Aggregation: When conditions become unfavorable, such as depletion of food or increase in population density, the individual cells release a chemical signal called cAMP (cyclic adenosine monophosphate). This signal attracts other cells, and they aggregate together to form a multicellular structure called a pseudoplasmodium.

3. Pseudoplasmodium Formation: The aggregation of cells leads to the formation of a slug-like pseudoplasmodium. This slug consists of thousands of cells that are tightly packed together. The slug moves as a cohesive unit, responding to environmental cues such as light and chemical gradients.

4. Migration and Differentiation: The pseudoplasmodium undergoes migration, moving towards a suitable location for spore formation. During this migration, the slug differentiates into different cell types, including stalk cells and spore cells.

5. Spore Formation: Eventually, the pseudoplasmodium stops migrating and forms a fruiting body. The stalk cells form a stalk, and the spore cells are lifted up to the top of the stalk. These spore cells differentiate into spores, which are released into the environment when the fruiting body bursts.

6. Germination of Spores: The spores are resistant to harsh environmental conditions and can survive until conditions become favorable again. When conditions are suitable, the spores germinate and give rise to new individual amoeboid cells, thus completing the life cycle.

Conclusion:
Pseudoplasmodium is a characteristic feature of cellular slime molds. It is a multicellular structure formed by the aggregation of individual amoeboid cells during certain stages of the cellular slime mold's life cycle.