The digestive tracts of ruminants contain:-

Options

A. Halophilic bacteria
B. Methanogens
C. Thermoacidophile bacteria
D. Mycoplasma

Answer

**Step-by-Step Solution:**

1. **Understanding Ruminants**: Ruminants are a group of animals that have a specialized stomach structure, which allows them to digest cellulose from plant materials through a process called fermentation.

2. **Identifying the Digestive Tract Components**: The digestive tracts of ruminants consist of multiple compartments, including the rumen, reticulum, omasum, and abomasum. The rumen is particularly important for fermentation.

3. **Role of Microorganisms**: The fermentation process in the rumen is facilitated by various microorganisms, including bacteria, protozoa, and fungi, which help break down cellulose into simpler compounds.

4. **Evaluating the Options**:
- **Halophilic Bacteria**: These are bacteria that thrive in high salt concentrations and are not typically found in the digestive tracts of ruminants.
- **Methanogens**: This group of archaebacteria is crucial in the digestive tracts of ruminants as they help convert by-products of fermentation (like formic acid and carbon dioxide) into methane. This process is essential for the overall fermentation of cellulose.
- **Thermo Acidophile Bacteria**: These bacteria thrive in acidic and high-temperature environments, which do not correspond to the conditions in the ruminant digestive tract.
- **Mycoplasma**: These are the smallest free-living prokaryotes, but they are not specifically associated with the fermentation process in ruminants.

5. **Conclusion**: Based on the evaluation of the options, the correct answer is **methanogens**, as they play a significant role in the fermentation process within the digestive tracts of ruminants.

**Final Answer**: The digestive tracts of ruminants contain **methanogens**.

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