Which of the following represents a disaccharide?

Sucrose is classified as a disaccharide because it is composed of two monosaccharides: glucose and fructose. Disaccharides are carbohydrates formed when two monosaccharide molecules undergo a dehydration reaction, linking them together with a glycosidic bond. In the case of sucrose, the bond is formed between the hydroxyl group of one sugar and the anomeric carbon of another, resulting in a substance that the body can metabolize for energy.

Glucose and galactose, on the other hand, are each monosaccharides, meaning they are the simplest forms of carbohydrates and cannot be hydrolyzed into smaller sugar units. Amino acids, while they do play a crucial role in nutrition and protein synthesis, are not carbohydrates and therefore do not fall within the classification of disaccharides or sugars at all. Thus, the only correct option representing a disaccharide is sucrose.