What is the main characteristic of a saturated hydrocarbon?

A saturated hydrocarbon is defined by its structure, which contains only single bonds between carbon atoms. This characteristic is crucial because the presence of double or triple bonds, as indicated in the other options, would categorize the hydrocarbon as unsaturated. Unsaturated hydrocarbons, such as alkenes and alkynes, feature one or more double or triple bonds, respectively, which introduce reactivity distinct from that of saturated hydrocarbons. Additionally, while aromatic rings represent a different class of hydrocarbons (arenes), they do not pertain to the saturated versus unsaturated distinction. Therefore, the defining attribute of a saturated hydrocarbon is the absence of multiple bonds, ensuring all carbon-carbon connections are single bonds, which makes the structure fully hydrogenated.