What term refers to single sugar compounds containing three to six carbons?

Monosaccharides are the fundamental building blocks of carbohydrates, characterized by their structure of single sugar units that typically contain three to six carbon atoms. The simplest form, a monosaccharide, includes examples like glucose (six carbons), fructose (six carbons), and ribose (five carbons). The 'mono-' prefix indicates that these sugars consist of a single unit, distinguishing them from larger carbohydrate structures.

In contrast, polysaccharides consist of long chains of monosaccharide units bonded together, while disaccharides are made up of two monosaccharide units. The term carbohydrates is a broader category that encompasses monosaccharides, disaccharides, and polysaccharides, but it does not specifically refer to the single sugar compounds themselves. Thus, monosaccharides accurately identifies the specific group of simple sugars with three to six carbons, making it the correct choice.