The gas released during the preparation of bread is

Options

A. oxygen
B. carbon dioxide
C. nitrogen
D. sulphur dioxide

Explanation

**Step-by-Step Solution:**

1. **Understanding Bread Preparation**: The process of making bread involves fermentation, which is a metabolic process where microorganisms convert sugars into alcohol and gases.

2. **Role of Yeast**: Yeast, a type of microorganism, plays a crucial role in the fermentation process. It consumes sugars (like glucose) and produces byproducts.

3. **Fermentation Process**: During fermentation, glucose is first converted into pyruvate through a series of reactions known as glycolysis.

4. **Production of Byproducts**: After glycolysis, the pyruvate is further processed to produce ethanol (alcohol) and carbon dioxide gas.

5. **Gas Release**: The specific gas released during the fermentation process in bread making is carbon dioxide (CO2). This gas is responsible for the rising of the dough.

6. **Conclusion**: Therefore, the gas released during the preparation of bread is carbon dioxide.

**Final Answer**: The gas released during the preparation of bread is carbon dioxide.

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