What distinguishes saturated compounds from unsaturated compounds?

Saturated compounds are defined as those that contain only single carbon-carbon bonds. This structural characteristic means that every carbon atom in a saturated compound has the maximum number of hydrogen atoms attached to it, fulfilling the tetravalency of carbon.

In contrast, unsaturated compounds contain at least one carbon-carbon double or triple bond, which means they do not have the maximum number of hydrogen atoms possible. Because of this unsaturation, they have the ability to participate in addition reactions, where reagents can add across the double or triple bonds.

The distinction primarily revolves around the nature of the carbon-carbon bonds; saturated compounds with single bonds have no such reactive sites available, while unsaturated compounds, with double or triple bonds, can readily react through addition. Thus, the correct choice emphasizes the single bonds present in saturated compounds, marking them as distinct from their unsaturated counterparts.