The first product of `C_(4)` pathway is

Options

A. oxaloacetic acid
B. RuBP
C. PGA
D. PGAL

Answer

To solve the question "The first product of the C4 pathway is," we will analyze the options provided and understand the C4 pathway in photosynthesis.

### Step-by-Step Solution:

1. **Understanding the C4 Pathway**:
- The C4 pathway is a photosynthetic process that occurs in certain plants (C4 plants) where carbon dioxide is fixed into a four-carbon compound. This is different from the C3 pathway, which produces a three-carbon compound.

2. **Identifying the First Product**:
- The first product of the C4 pathway is a four-carbon compound. This compound is crucial as it is formed when carbon dioxide is initially fixed.

3. **Evaluating the Options**:
- **Option 1: Oxaloacetic Acid (OAA)**: This is a four-carbon compound and is indeed the first product of the C4 pathway.
- **Option 2: RuBP (Ribulose bisphosphate)**: This is a five-carbon compound involved in the Calvin cycle (C3 pathway), not the C4 pathway.
- **Option 3: PGA (Phosphoglyceric Acid)**: This is a three-carbon compound and is the first product of the Calvin cycle, not the C4 pathway.
- **Option 4: PGAL (Phosphoglyceraldehyde)**: This is also an intermediate in the Calvin cycle and not related to the C4 pathway.

4. **Conclusion**:
- Based on the analysis, the first product of the C4 pathway is **Oxaloacetic Acid (OAA)**. Therefore, the correct answer is **Option 1**.

### Final Answer:
The first product of the C4 pathway is **Oxaloacetic Acid (OAA)**.

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