Chitin, found in fungal cell walls and arthropod exoskeletons, is an unbranched polymer consisting solely of N-acetyl-D-glucosamine (GlcNAc) units joined by $\beta-(1\rightarrow 4)$ glycosidic bonds.

Inulin is a naturally occurring storage fructan polysaccharide consisting of linear chains of D-fructose units linked by $\beta-(2\rightarrow 1)$ glycosidic bonds, often terminating with a glucose residue.

All four compounds—Heparin, Dermatan sulfate, Chondroitin sulfate, and Hyaluronic acid—are classic glycosaminoglycans (GAGs), unbranched heteropolysaccharides composed of repeating disaccharide units (an amino sugar and an uronic acid or galactose).

Carbohydrates are chemically defined as polyhydroxy aldehydes or ketones (D), originally described empirically as hydrates of carbon with general formula $C_n(H_2O)_n$ (C), containing a minimum of three carbons (trioses like glyceraldehyde/dihydroxyacetone) (A). Polyhydroxy alcohols without carbonyl groups (like glycerol or sorbitol) are sugar alcohols (alditols), not true carbohydrates.