Bacteria that live in most harsh habitats are

Options

A. eubacteria
B. cyanobacteria
C. mycoplasma
D. archaebacteria

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:** The question asks about bacteria that thrive in the most extreme or harsh habitats.

2. **Identifying the Options:**
- Eubacteria
- Cyanobacteria
- Mycoplasma
- Archaebacteria

3. **Analyzing Each Option:**
- **Eubacteria:** These are the "true" bacteria found in various environments, including deep oceans and freshwater. They do not typically inhabit the most extreme environments.
- **Cyanobacteria:** Also known as blue-green algae, these bacteria are primarily found in freshwater and marine environments. They are not specifically adapted to extreme conditions.
- **Mycoplasma:** These are a type of bacteria that lack a cell wall and are found in the mucous surfaces of respiratory and urogenital tracts. They do not inhabit harsh environments.
- **Archaebacteria:** These are known for their ability to live in extreme conditions. They are categorized into three main types:
- **Halophiles:** Thrive in highly saline environments (e.g., salt lakes).
- **Thermophiles:** Live in extremely hot environments (e.g., hot springs).
- **Methanogens:** Found in anaerobic environments, such as marshy areas, and produce methane gas.

4. **Conclusion:** Based on the analysis, the bacteria that live in the most harsh habitats are **Archaebacteria**.

5. **Final Answer:** The correct option is **Archaebacteria**.

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