Select the incorrect pair.

Options

A. 2-carbon compound-Aspartic acid
B. 3-carbon compound-PGA
C. 4-carbon compound-Malic acid
D. 5-carbon compound-RuBP

Explanation

To solve the question "Select the incorrect pair," we need to analyze each option provided and determine whether the carbon compound classification is accurate.

### Step-by-Step Solution:

1. **Identify the Options:**
- Option 1: Aspartic acid - 2 carbon compound
- Option 2: Phosphoglycerate - 3 carbon compound
- Option 3: Malic acid - 4 carbon compound
- Option 4: RuBP (Ribulose 1,5-bisphosphate) - 5 carbon compound

2. **Analyze Each Option:**
- **Option 1: Aspartic acid**
- The molecular formula of aspartic acid is C4H7NO4.
- This indicates that aspartic acid is a 4 carbon compound, not a 2 carbon compound.
- Therefore, this option is incorrect.

- **Option 2: Phosphoglycerate**
- The molecular formula of phosphoglycerate is C3H7O7P.
- This confirms that phosphoglycerate is indeed a 3 carbon compound.
- This option is correct.

- **Option 3: Malic acid**
- The molecular formula of malic acid is C4H6O5.
- This shows that malic acid is a 4 carbon compound.
- This option is correct.

- **Option 4: RuBP**
- The molecular formula of RuBP is C5H12O11P2.
- This indicates that RuBP is a 5 carbon compound.
- This option is correct.

3. **Conclusion:**
- The only incorrect pair is Option 1: Aspartic acid as a 2 carbon compound. The correct classification is that aspartic acid is a 4 carbon compound.

### Final Answer:
The incorrect pair is **Option 1: Aspartic acid - 2 carbon compound**.