Assertion : Fermentation occurs by incomplete oxidation of glucose.
Reason : Yeast form ethanol & `CO_(2)` from pyruvic acid.

Options

A. Both A and R are true and R is the correct explanation of A.
B. Both A and R are true but R is not correct explanation of A
C. A is true but R is false
D. A and R are false

Answer

To analyze the given assertion and reason, we will break down the concepts of fermentation and the role of yeast in this process.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Fermentation occurs by incomplete oxidation of glucose."
- Fermentation is a metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen. It is indeed characterized by the incomplete oxidation of glucose.

2. **Understanding the Reason**:
- The reason states that "Yeast form ethanol and CO2 from pyruvic acid."
- Yeast, particularly the species Saccharomyces cerevisiae, performs alcoholic fermentation where pyruvic acid (produced from glycolysis) is converted into ethanol and carbon dioxide. This process is an example of fermentation.

3. **Evaluating the Truth of Each Statement**:
- Both the assertion and the reason are true statements. Fermentation is indeed an incomplete oxidation process, and yeast does convert pyruvic acid into ethanol and CO2.

4. **Analyzing the Relationship**:
- Although both statements are true, the reason does not serve as a correct explanation for the assertion. The assertion is about the overall process of fermentation being an incomplete oxidation, while the reason specifically describes a step in the fermentation process.

5. **Conclusion**:
- The assertion is true, and the reason is also true, but the reason does not explain the assertion. Therefore, the correct option is that both statements are true, but the reason is not a correct explanation of the assertion.

### Final Answer:
- Assertion: True
- Reason: True
- Relationship: Reason is not a correct explanation of the assertion.

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