The first stable product in `CAM//C_(4)` plants is

Options

A. malic acid
B. oxalo acetic acid
C. phosphogylyceric acid
D. aspartic acid

Answer

To answer the question about the first stable product in CAM (Crassulacean Acid Metabolism) and C4 plants, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding CAM and C4 Plants**:
- CAM and C4 plants have a specialized method of photosynthesis that allows them to efficiently fix carbon dioxide (CO2) in environments where water is scarce.
- Both types of plants initially fix CO2 into a four-carbon compound.

2. **Identifying the Initial CO2 Fixation**:
- In both CAM and C4 plants, the initial fixation of CO2 occurs with the help of a compound called phosphoenolpyruvate (PEP).
- PEP reacts with CO2 to form a four-carbon compound.

3. **Determining the First Stable Product**:
- The first stable product formed after the reaction of CO2 with PEP is oxaloacetic acid (OAA).
- OAA is a four-carbon compound and is crucial in both CAM and C4 pathways.

4. **Further Conversion**:
- In C4 plants, OAA can be converted into malic acid (another four-carbon compound), but OAA is the first stable product formed.
- It is important to note that phosphoglyceric acid (PGA) is associated with C3 plants and is not the first product in CAM or C4 plants.

5. **Conclusion**:
- Therefore, the correct answer to the question is oxaloacetic acid (OAA), which is the first stable product in CAM and C4 plants.

### Final Answer:
The first stable product in CAM and C4 plants is **oxaloacetic acid**.