Which of the following processes is the source of energy in chemoautotrophs for fixation of `CO_2` into carbohydrates ?

Options

A. Oxidation of inorganic molecules
B. Oxidation of organic molecules
C. Reduction of organic molecules
D. Reduction/oxidation of any matter present in medium.

Answer

To answer the question regarding the source of energy in chemoautotrophs for the fixation of CO2 into carbohydrates, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Chemoautotrophs**:
- Chemoautotrophs are organisms that can produce their own food using inorganic substances. They do this through a process called chemosynthesis, where they utilize chemical energy.

2. **Energy Source**:
- Unlike photosynthetic organisms that use sunlight as their energy source, chemoautotrophs derive their energy from the oxidation of inorganic molecules. These inorganic molecules can include substances like hydrogen sulfide, ammonia, or ferrous iron.

3. **Carbon Dioxide Fixation**:
- Chemoautotrophs fix carbon dioxide (CO2) to produce organic molecules, primarily carbohydrates. This process is essential for their survival and growth.

4. **Oxidation of Inorganic Molecules**:
- The energy required for the fixation of CO2 comes from the oxidation of these inorganic chemicals. This means that as these inorganic substances are oxidized, they release energy that is then used to convert CO2 into carbohydrates.

5. **Conclusion**:
- Therefore, the correct answer to the question is that the source of energy in chemoautotrophs for the fixation of CO2 into carbohydrates is the **oxidation of inorganic molecules**.

### Final Answer:
The source of energy in chemoautotrophs for the fixation of CO2 into carbohydrates is the **oxidation of inorganic molecules**.

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