Which of the following is NOT a type of carbohydrate?

Flavonoids are a class of plant secondary metabolites that are known for their role in pigmentation and their antioxidant properties, but they do not fall under the category of carbohydrates. Carbohydrates, primarily composed of carbon, hydrogen, and oxygen, include sugars, starches, and fibers, which serve various functions such as energy storage and structural components in plants.

Sugar acids, gums and mucilages, and sugar alcohols are all associated with carbohydrates in some form. For instance, sugar acids derive from the oxidation of sugars, while gums and mucilages are polysaccharides that serve other roles beyond energy storage. Sugar alcohols are reduced forms of sugars that also provide energy. Therefore, the identification of flavonoids as a distinct group of compounds separate from carbohydrates supports why they are not classified as such.