Most of the homeostatic mechanisms operate through feed back mechanism. The best example is illustrated by

Options

A. hormones
B. enzymes
C. vitamins
D. ribozymes

Answer

### Step-by-Step Solution:

1. **Understanding Homeostasis**: Homeostasis refers to the maintenance of stable internal conditions in an organism despite changes in the external environment. This involves various physiological processes that regulate temperature, pH, hydration, and other vital parameters.

2. **Feedback Mechanisms**: Homeostatic mechanisms often operate through feedback loops. These can be classified into two main types:
- **Negative Feedback Mechanism**: This mechanism reduces the output or activity of a system when it deviates from a set point. For example, when body temperature rises, mechanisms are activated to cool the body down.
- **Positive Feedback Mechanism**: This mechanism enhances or amplifies changes or outputs in a system. An example is the process of childbirth, where the release of oxytocin increases contractions, leading to more oxytocin release.

3. **Role of Hormones**: Hormones play a crucial role in maintaining homeostasis through feedback mechanisms. They are chemical messengers that regulate various bodily functions and can trigger both positive and negative feedback loops.

4. **Example of Hormonal Feedback**:
- **Negative Feedback**: When the concentration of a hormone (like cortisol) increases, it can inhibit the release of the hormone that stimulates its production (like adrenocorticotropic hormone, ACTH).
- **Positive Feedback**: During childbirth, the release of oxytocin increases uterine contractions, which in turn stimulates more oxytocin release.

5. **Conclusion**: The best example of homeostatic mechanisms operating through feedback is the hormonal system in the body, which utilizes both negative and positive feedback to maintain internal balance.

### Final Answer:
The best example of homeostatic mechanisms operating through feedback is illustrated by **hormones**.

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