The optically active tartaric acid is named as `D-(+)-` tartaric acid because it has a positive

Options

A. Optical rotation and is derived from `D`-glucose.
B. `pH` in organic solvent.
C. Optical rotation and is derived from `D-(+)-` glyceral-dehyde.
D. Optical rotation when substituted by deuterium.

Explanation

To solve the question regarding why the optically active tartaric acid is named `D-(+)-` tartaric acid, we can break down the reasoning step by step.

### Step-by-Step Solution:

1. **Understanding Tartaric Acid**:
- Tartaric acid is a naturally occurring organic acid that has two carboxylic acid groups (-COOH) and multiple hydroxyl groups (-OH). It is a chiral molecule, meaning it has non-superimposable mirror images (enantiomers).

2. **Optical Activity**:
- Optical activity refers to the ability of a compound to rotate plane-polarized light. The direction of this rotation can be either to the right (clockwise) or to the left (counterclockwise). Compounds that rotate light to the right are designated as (+) or "dextrorotatory," while those that rotate light to the left are designated as (-) or "levorotatory."

3. **D-Configuration**:
- The "D" in `D-(+)-` tartaric acid refers to the configuration of the molecule based on the reference compound D-glyceraldehyde. In D-glyceraldehyde, the hydroxyl group (-OH) on the penultimate carbon (the second last carbon) is on the right side when the molecule is drawn in a Fischer projection.

4. **Positive Optical Rotation**:
- The (+) sign indicates that the compound has a positive optical rotation, meaning it rotates plane-polarized light to the right. This is a characteristic of the specific stereoisomer of tartaric acid that is derived from D-glyceraldehyde.

5. **Conclusion**:
- Therefore, `D-(+)-` tartaric acid is named so because it is derived from D-glyceraldehyde and exhibits positive optical rotation.

### Final Answer:
The correct answer is that `D-(+)-` tartaric acid is named because it has a positive optical rotation and is derived from D-glyceraldehyde.

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