Which is not a natural source of `CH_(4)` in the environment

Options

A. Biomass burning
B. Termites
C. Gut of ruminants
D. Rice fields

Answer

To determine which option is not a natural source of methane (CH₄) in the environment, we will analyze each given option step by step.

### Step-by-Step Solution:

1. **Understanding Methane (CH₄)**:
- Methane is a greenhouse gas that contributes to the greenhouse effect. It is produced through various natural processes.

2. **Analyzing the Options**:
- **Option A: Biomass Burning**:
- Biomass refers to plant and animal matter used as fuel. When biomass is burned, it can produce methane. However, biomass burning can occur both naturally (e.g., wildfires) and through human activities (e.g., controlled burns for agriculture). Thus, it is not exclusively a natural source of methane.

- **Option B: Burning Termites**:
- Termites are insects that break down wood and leaves in their diet, producing methane as a by-product through their gut bacteria. This process is natural and contributes to methane emissions.

- **Option C: Gut of Ruminants**:
- Ruminants, such as cows and sheep, have microorganisms (methanogens) in their digestive systems that produce methane during digestion. This is a natural process and a significant source of methane.

- **Option D: Rice Fields**:
- Wetland rice fields are known to produce methane due to anaerobic fermentation of organic matter in flooded conditions. This is also a natural process.

3. **Conclusion**:
- After analyzing all options, the only one that is not exclusively a natural source of methane is **biomass burning**. While it can occur naturally, it can also be caused by human intervention, making it the correct answer to the question.

### Final Answer:
**Biomass burning** is not a natural source of CH₄ in the environment.

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