Bacteria and fungi are

Options

A. Scavengers
B. Primary consumers
C. Secondary consumers
D. Decomposers

Explanation

**Step-by-Step Solution:**

1. **Understanding the Role of Bacteria and Fungi**: Begin by identifying what bacteria and fungi are in the context of an ecosystem. They are microorganisms that play a crucial role in the decomposition process.

2. **Identifying the Types of Organisms in an Ecosystem**: In an ecosystem, organisms can be categorized into producers, consumers, scavengers, and decomposers. Producers (like plants) create energy, consumers (herbivores and carnivores) consume energy, scavengers feed on dead organisms, and decomposers break down dead organic matter.

3. **Defining Decomposers**: Decomposers are organisms that break down dead and decaying organic material, returning essential nutrients to the soil. This process is vital for nutrient cycling in ecosystems.

4. **Recognizing the Characteristics of Bacteria and Fungi**: Both bacteria and fungi are classified as saprophytic organisms, meaning they obtain their nutrients from dead or decaying organic matter. This characteristic aligns them with the role of decomposers.

5. **Conclusion**: Based on the definitions and roles of these organisms, we can conclude that bacteria and fungi are decomposers in an ecosystem.

6. **Final Answer**: Therefore, the correct classification for bacteria and fungi is that they are decomposers.

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