Which of the following is not reducing sugar.

Options

A. Sucrose
B. Glucose and fructose
C. Fructose
D. maltose

Explanation

To determine which of the following sugars is not a reducing sugar, we need to understand the concept of reducing sugars and analyze each option provided.

### Step-by-Step Solution:

1. **Understanding Reducing Sugars:**
- Reducing sugars are carbohydrates that can donate electrons to another chemical, thus reducing it. This typically occurs because they have a free anomeric carbon (the carbon that is part of the hemiacetal or hemiketal structure).

2. **Analyzing Each Option:**
- **Option A: Sucrose**
- Sucrose is a disaccharide composed of glucose and fructose. In its structure, both anomeric carbons (from glucose and fructose) are involved in the glycosidic bond, meaning they are not free. Therefore, sucrose does not have a free anomeric carbon and is classified as a non-reducing sugar.

- **Option B: Glucose**
- Glucose is a monosaccharide and has a free anomeric carbon. Therefore, glucose is a reducing sugar.

- **Option C: Fructose**
- Fructose is also a monosaccharide with a free anomeric carbon. Thus, fructose is a reducing sugar as well.

- **Option D: Maltose**
- Maltose is a disaccharide made of two glucose units. In its structure, one anomeric carbon is free, allowing maltose to act as a reducing sugar.

3. **Conclusion:**
- Based on the analysis, the only sugar that is not a reducing sugar is **sucrose**.

### Final Answer:
**Sucrose is not a reducing sugar.**

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