Answer:
The correct answer is option a. "kingdom fungi".
Step-by-step explanation:
The kingdom fungi contains plenty of organisms that are decomposers. Most fungi act as decomposers in ecosystems by feeding from decaying organic matter and returning nutrients to the soil, which are later used by the plants. The fungi that are decomposers are known as saprotrophs, and are very important for its role in decomposing the cellulose from plant cell walls.