**Core Concept**
Reduction sugars are a class of carbohydrates that can donate electrons to other molecules, resulting in a reduction reaction. This property is a key characteristic of these sugars and is utilized in various biochemical assays, including the Benedict's test.

**Why the Correct Answer is Right**
The correct answer is a reducing sugar because it contains an aldehyde or ketone group, which can participate in a reduction reaction. This group is responsible for the sugar's ability to donate electrons to other molecules. In the case of glucose, the aldehyde group is located at the end of the sugar molecule, making it a reducing sugar.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not contain an aldehyde or ketone group, making it a non-reducing sugar.
**Option B:** This option is incorrect because it is a disaccharide, which means it is composed of two sugar molecules bonded together. Non-reducing disaccharides do not have a free aldehyde or ketone group, making them non-reducing.

**Clinical Pearl / High-Yield Fact**
Reducing sugars are commonly found in nature and play a crucial role in various biochemical processes. The ability to distinguish between reducing and non-reducing sugars is essential in clinical settings, where it can help diagnose conditions such as diabetes.

**Correct Answer:** A. Glucose