Which of the following is a characteristic of alkanes?

Alkanes are defined as saturated hydrocarbons, meaning that they contain only single bonds between carbon atoms. This saturation indicates that each carbon atom is bonded to the maximum number of hydrogen atoms possible, following the general formula CnH2n+2, where n is the number of carbon atoms. The presence of only single bonds makes alkanes relatively stable and less reactive compared to other types of hydrocarbons, such as alkenes and alkynes, which contain double and triple bonds, respectively.

While alkanes can indeed form cyclic structures, that characteristic is also shared with alkenes and other types of compounds, making it less distinctive of alkanes. The reactivity of alkanes is generally low due to their saturated nature, which is contrary to the characteristics highlighted in the question. Therefore, the defining feature of alkanes is their status as saturated hydrocarbons.