Bacteria that get their energy by fermentation and oxygen is lethal for them are called :

Options

A. obligate aerobes
B. obligate anaerobes
C. facultative aerobes
D. facultative anaerobes

Explanation

To solve the question regarding the type of bacteria that obtain their energy through fermentation and are harmed by the presence of oxygen, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of Bacteria**:
- We need to identify the different classifications of bacteria based on their oxygen requirements: obligate aerobes, obligate anaerobes, facultative aerobes, and facultative anaerobes.

2. **Analyze Obligate Aerobes**:
- Obligate aerobes are bacteria that require oxygen for their growth and metabolism. Since oxygen is essential for them, they cannot be the answer to our question.

3. **Analyze Obligate Anaerobes**:
- Obligate anaerobes are bacteria that obtain energy through fermentation and cannot tolerate oxygen. In fact, oxygen is lethal to them, as they have metabolic pathways that do not function in its presence. This matches the criteria given in the question.

4. **Analyze Facultative Aerobes**:
- Facultative aerobes can grow in the presence or absence of oxygen. They can utilize oxygen when available but can also ferment when oxygen is not present. Thus, they do not fit the description of being harmed by oxygen.

5. **Analyze Facultative Anaerobes**:
- Facultative anaerobes can also survive in both conditions: with or without oxygen. They can perform fermentation in the absence of oxygen and aerobic respiration when oxygen is available. Therefore, they do not meet the criteria of being harmed by oxygen.

6. **Conclusion**:
- Based on the analysis, the only type of bacteria that fits the description of obtaining energy through fermentation and being harmed by oxygen is **Obligate Anaerobes**.

### Final Answer:
The bacteria that get their energy by fermentation and find oxygen lethal are called **Obligate Anaerobes**.

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