Maintaining the constancy of internal environment is called.

Options

A. Homeostasis
B. Diapause
C. Hibernation
D. Aestivation

Answer

To solve the question "Maintaining the constancy of internal environment is called," we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks for the term that describes the process of maintaining a stable internal environment within an organism.

2. **Review the Options**: The options provided are:
- Homeostasis
- Diapause
- Hibernation
- Estivation

3. **Analyze Each Option**:
- **Homeostasis**: This term refers to the ability of an organism to maintain a stable internal environment despite changes in external conditions. It involves various physiological processes that regulate factors such as temperature, pH, and electrolyte balance.
- **Diapause**: This is a period of suspended development in organisms, often in response to adverse environmental conditions, but it does not refer to maintaining internal constancy.
- **Hibernation**: This is a state of dormancy that some animals enter during winter to conserve energy, but it is not related to the ongoing maintenance of internal conditions.
- **Estivation**: Similar to hibernation, this is a dormant state that occurs during hot or dry periods, primarily to avoid extreme temperatures.

4. **Identify the Correct Answer**: Based on the definitions and functions of each term, the correct answer is **Homeostasis**. This is the only term that directly relates to the maintenance of a stable internal environment.

5. **Conclusion**: Therefore, the answer to the question is **Homeostasis**.