Which of the following is classified as a monosaccharide?

Fructose is classified as a monosaccharide because it consists of a single sugar molecule. Monosaccharides are the simplest form of carbohydrates, and they cannot be hydrolyzed into smaller carbohydrate molecules. Other examples of monosaccharides include glucose and galactose.

In contrast, sucrose, lactose, and maltose are disaccharides and oligosaccharides composed of two or more monosaccharide units. Sucrose is made up of glucose and fructose, lactose comprises glucose and galactose, while maltose consists of two glucose units. This structural difference is fundamental in classifying sugars based on the number of sugar units they contain, with monosaccharides being the building blocks for more complex carbohydrates.