The Organisms which make break down complex organic substances into simpler inorganic substances and mix them in soil :

Options

A. Producers
B. Decomposers
C. Herbivores
D. Carnivores

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks about organisms that break down complex organic substances into simpler inorganic substances and mix them into the soil.

2. **Identifying the Organisms**: The organisms that perform this function are known as **decomposers**. They play a crucial role in the ecosystem by recycling nutrients.

3. **Role of Decomposers**: Decomposers feed on dead and decaying matter, which can include both plant and animal remains. They help in the breakdown of these organic substances.

4. **Types of Decomposers**: The primary types of decomposers are certain **bacteria** and **fungi**. These organisms are also referred to as **saprophytes** when they feed on dead organic matter.

5. **Process of Decomposition**: Decomposers utilize enzymes to break down complex organic substances into simpler inorganic substances. This process is essential for nutrient cycling.

6. **Nutrient Availability**: The inorganic substances produced through decomposition are then mixed back into the soil, making them available for **producers** (like plants) to use for growth.

7. **Conclusion**: Therefore, the correct answer to the question is **decomposers**, which include specific bacteria and fungi that break down organic matter and enrich the soil with nutrients.