Which of the following is a 4-carbon compound?

Options

A. Oxaloacetic acid
B. Phosphoglyceric acid
C. Ribulose bisphosphate
D. Phosphoenol pyruvate

Explanation

To determine which of the given options is a 4-carbon compound, we will analyze each option one by one based on their chemical formulas.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are:
- A) Oxaloacetic acid
- B) Phosphoglyceric acid
- C) Ribulose bisphosphate
- D) Phosphoenolpyruvate

2. **Analyze Option A: Oxaloacetic Acid**:
- The empirical formula of oxaloacetic acid is C4H4O5.
- Here, we can see that there are 4 carbon atoms (C4).
- **Conclusion**: This is a 4-carbon compound.

3. **Analyze Option B: Phosphoglyceric Acid**:
- The empirical formula of phosphoglyceric acid is C3H7O7P.
- Here, we can see that there are 3 carbon atoms (C3).
- **Conclusion**: This is not a 4-carbon compound.

4. **Analyze Option C: Ribulose Bisphosphate**:
- The empirical formula of ribulose bisphosphate is C5H12O11P2.
- Here, we can see that there are 5 carbon atoms (C5).
- **Conclusion**: This is not a 4-carbon compound.

5. **Analyze Option D: Phosphoenolpyruvate**:
- The empirical formula of phosphoenolpyruvate is C3H5O6P.
- Here, we can see that there are 3 carbon atoms (C3).
- **Conclusion**: This is not a 4-carbon compound.

6. **Final Conclusion**:
- After analyzing all options, we find that the only 4-carbon compound is **Oxaloacetic Acid** (Option A).