Biological equilibrium is an equilibrium among the:

Options

A. Producers and consumers
B. Producers and decomposers
C. Producers, consumers, and decomposers
D. Producers and light

Answer

**Step-by-Step Solution:**

1. **Understanding Biological Equilibrium**: Biological equilibrium refers to a state in an ecosystem where the populations of different organisms (species) remain relatively stable over time. This stability is achieved when the interactions among various groups of organisms are balanced.

2. **Identifying Key Components of an Ecosystem**: An ecosystem consists of three main types of organisms:
- **Producers**: These are organisms, primarily plants, that produce energy through photosynthesis.
- **Consumers**: These are organisms that consume producers or other consumers for energy. They can be herbivores, carnivores, or omnivores.
- **Decomposers**: These organisms, such as fungi and bacteria, break down dead organic matter, recycling nutrients back into the ecosystem.

3. **Explaining the Dynamic Balance**: For an ecosystem to be in biological equilibrium, there must be a dynamic balance among producers, consumers, and decomposers. This means that the populations of these groups should be in a state where they can sustain each other without significant fluctuations that could lead to collapse or overgrowth.

4. **Considering the Options**: The question presents four options:
- A) Producers and consumers
- B) Producers and decomposers
- C) Producers, consumers, and decomposers
- D) Producers and light

5. **Evaluating the Options**:
- Option A (Producers and consumers) does not include decomposers, which play a crucial role in nutrient cycling.
- Option B (Producers and decomposers) misses out on consumers, which are essential for energy transfer.
- Option C (Producers, consumers, and decomposers) includes all three groups, which is necessary for a balanced ecosystem.
- Option D (Producers and light) does not address the roles of consumers and decomposers.

6. **Conclusion**: The correct answer is option C, as biological equilibrium is achieved when there is a balance among producers, consumers, and decomposers in an ecosystem.

**Final Answer**: Biological equilibrium is an equilibrium among the **producers, consumers, and decomposers** (Option C).

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