Assertion `:` Glucose reacts with phenyl hydrazine and Fehling's solution but not with `NaHSO_(3)`.
Reason`:` `NaHSO_(3)` cannot break the ring structure.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that glucose reacts with phenyl hydrazine and Fehling's solution but does not react with NaHSO₃ (sodium bisulfite).
- Glucose is a monosaccharide that contains both an aldehyde group and alcoholic (hydroxyl) groups.

2. **Reactions of Glucose**:
- **With Phenyl Hydrazine**: Glucose can react with phenyl hydrazine to form a hydrazone. This reaction occurs because glucose has an aldehyde functional group, which is reactive towards phenyl hydrazine.
- **With Fehling's Solution**: Fehling's solution is used to test for reducing sugars. Glucose, being a reducing sugar due to its aldehyde group, will react with Fehling's solution, resulting in a color change.
- **With NaHSO₃**: Sodium bisulfite typically reacts with free aldehyde groups to form bisulfite addition products. However, in the case of glucose, the aldehyde group is involved in a cyclic structure (pyranose form), and thus it is not free to react.

3. **Understanding the Reason**:
- The reason states that NaHSO₃ cannot break the ring structure of glucose.
- This is true because the cyclic form of glucose (pyranose) does not have a free aldehyde group available for reaction with NaHSO₃. The ring structure prevents the formation of the bisulfite addition product.

4. **Conclusion**:
- Both the assertion and the reason are true.
- The reason provided correctly explains why glucose does not react with NaHSO₃, which is due to the presence of the cyclic structure that does not allow for the free aldehyde group to participate in the reaction.

### Final Answer:
Both assertion and reason are true, and the reason is the correct explanation of the assertion.