What is the primary feature of an alkane?

The primary feature of an alkane is that it is a saturated hydrocarbon with only single bonds between carbon atoms. This means that each carbon atom in an alkane is bonded to the maximum number of hydrogen atoms possible, leading to the general formula (C_nH_{2n+2}), where (n) represents the number of carbon atoms in the molecule. This saturation distinguishes alkanes from other hydrocarbons, such as alkenes and alkynes, which contain one or more double or triple bonds, respectively.

In contrast, the other options mention characteristics inconsistent with alkanes. For instance, alkenes are the ones that feature double bonds, and the presence of oxygen is not essential for the structure of alkanes. The general formula provided in one of the options is also incorrect, as it does not reflect the correct relationship between the number of carbon and hydrogen atoms in alkanes. Thus, the defining attribute of alkanes being saturated hydrocarbons with single bonds is accurately represented in the choice selected.