`CO_(2)` fixation in bundle sheath cells occur in

Options

A. `C_(4)` plants
B. `C_(3)` plants
C. CAM
D. all of these

Answer

To determine where CO₂ fixation occurs in bundle sheath cells, we need to analyze the different types of plants and their respective processes of carbon dioxide fixation.

### Step-by-Step Solution:

1. **Understanding CO₂ Fixation**: CO₂ fixation refers to the process where carbon dioxide is converted into organic compounds, primarily during photosynthesis. This process is crucial for plant growth and energy production.

2. **Identifying Plant Types**:
- **C3 Plants**: In C3 plants, the primary site of CO₂ fixation is in the mesophyll cells. They do not have significant CO₂ fixation occurring in bundle sheath cells.
- **C4 Plants**: In C4 plants, CO₂ fixation initially occurs in the mesophyll cells where CO₂ is fixed to form oxaloacetic acid (OAA). This OAA is then converted into malate, which is transported to the bundle sheath cells. In the bundle sheath cells, the malate is decarboxylated to release CO₂ for the Calvin cycle, which occurs here.
- **CAM Plants**: In CAM (Crassulacean Acid Metabolism) plants, CO₂ fixation occurs at night when the stomata are open, and it is stored as malate. During the day, the malate is converted back to CO₂ for the Calvin cycle. This process does not specifically involve bundle sheath cells.

3. **Conclusion**: Since CO₂ fixation in bundle sheath cells is a characteristic feature of C4 plants (where the Calvin cycle occurs), the correct answer to the question is that CO₂ fixation in bundle sheath cells occurs in **C4 plants**.

### Final Answer:
**C4 plants (Option 1)**

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