Assertion: Due to pollution atmospheric concentration of `CO_(2)` is increasing which will be harmful for `C_(4)` plants whereas productive for `C_(3)`. plants.
Reasons : `C,_(4)` plants have greater efficiency for `CO_(2)` as `CO_(2)` is fixed by PEP oxygenase.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that due to pollution, the atmospheric concentration of CO2 is increasing, which is harmful for C4 plants but productive for C3 plants.
- **Analysis**: C4 plants are generally more efficient in fixing CO2 at lower concentrations compared to C3 plants. However, at elevated CO2 levels, C3 plants can benefit more because they can increase their rate of photosynthesis significantly.

2. **Understanding the Reason**: The reason provided is that C4 plants have greater efficiency for CO2 because CO2 is fixed by PEP oxygenase.
- **Analysis**: This statement is partially correct. C4 plants do have a greater efficiency for CO2 fixation, but they utilize an enzyme called PEP carboxylase, not PEP oxygenase. PEP carboxylase has a higher affinity for CO2, which allows C4 plants to effectively fix CO2 even at lower concentrations.

3. **Evaluating the Relationship**: The assertion is true because C3 plants can utilize the increased CO2 levels more effectively than C4 plants in polluted environments. The reason is false because it incorrectly identifies the enzyme responsible for CO2 fixation in C4 plants.

4. **Conclusion**: Since the assertion is true and the reason is false, the correct answer is that the assertion is true but the reason is false.

### Final Answer:
C) Assertion is true, but reason is false.

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