Which type of sugar is characterized by having three carbon atoms?

The type of sugar characterized by having three carbon atoms is indeed a triose. Triose sugars belong to the class of carbohydrates and are specifically monosaccharides, which are the simplest form of sugar. The term "triose" indicates that the molecule contains three carbon atoms in its structure, which is fundamental in the classification of sugars.

Monosaccharides can be categorized based on the number of carbon atoms they contain. For instance, tetrose sugars have four carbon atoms, pentose sugars have five, and hexose sugars possess six carbon atoms. Thus, the classification directly relates to the number of carbon atoms, making the triose category unique to sugars containing exactly three carbon atoms.