`CO_2` is produced in atmosphere by
respiration
burning of fossil fuels
volcanic eruptions
Identify the correct option(s).

Options

A. I and II
B. II and III
C. Only I
D. All of these

Answer

To solve the question regarding the production of `CO_2` in the atmosphere, we will analyze each of the given processes: respiration, burning of fossil fuels, and volcanic eruptions.

### Step-by-Step Solution:

1. **Understanding Respiration**:
- Respiration is a biological process where glucose (C6H12O6) is oxidized to produce energy. The general equation for respiration can be represented as:
\[ C6H12O6 + O2 \rightarrow CO2 + H2O + \text{Energy (ATP)} \]
- In this process, `CO_2` is released as a byproduct. Therefore, respiration contributes to the atmospheric `CO_2`.

2. **Analyzing Burning of Fossil Fuels**:
- The burning of fossil fuels is a combustion reaction where hydrocarbons react with oxygen. A common example is the combustion of methane (CH4):
\[ CH4 + O2 \rightarrow CO2 + H2O \]
- This reaction also produces `CO_2` as a byproduct. Hence, the burning of fossil fuels also contributes to the increase of `CO_2` in the atmosphere.

3. **Examining Volcanic Eruptions**:
- Volcanic eruptions release a variety of gases, including `CO_2`. During an eruption, gases trapped in magma are expelled, and `CO_2` is one of the significant gases released.
- Thus, volcanic eruptions are another source of `CO_2` in the atmosphere.

4. **Conclusion**:
- All three processes—respiration, burning of fossil fuels, and volcanic eruptions—produce `CO_2` in the atmosphere. Therefore, the correct answer to the question is that `CO_2` is produced by all of these processes.

### Final Answer:
The correct option is **all of these** (Option 4).

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