Fungi and bacteria grow mostly in which layer of soil?

Options

A. Subsoil
B. Topsoil
C. Bedrock
D. None of the above

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the specific layer of soil where fungi and bacteria, which are types of microorganisms, predominantly grow.

2. **Identifying Microorganisms**: Fungi and bacteria are classified as decomposers. They play a crucial role in breaking down dead and decaying organic matter.

3. **Role of Decomposers**: These microorganisms help in the decomposition process, converting dead organic material into humus, which is a dark, nutrient-rich component of soil.

4. **Identifying Soil Layers**: The soil is divided into different layers: topsoil, subsoil, bedrock, and sometimes others. Each layer has different characteristics and compositions.

5. **Locating Humus**: Humus is primarily found in the topsoil layer. This layer is rich in organic matter and is essential for soil fertility.

6. **Conclusion**: Since fungi and bacteria (decomposers) thrive in the layer where humus is present, the correct answer to the question is that they grow mostly in the **topsoil** layer of soil.

**Final Answer**: Fungi and bacteria grow mostly in the **topsoil** layer of soil.

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