What is a characteristic of the chemical structure of alkanes?

Alkanes are a class of hydrocarbons characterized specifically by their chemical structure, which consists only of single bonds between carbon atoms. This results in a saturated compound, meaning that each carbon atom is fully bonded to hydrogen atoms and cannot accommodate any additional atoms without breaking these bonds. The absence of double or triple bonds distinguishes alkanes from other types of hydrocarbons such as alkenes or alkynes, which feature multiple bonds. This structural feature contributes to the relatively low reactivity of alkanes compared to other hydrocarbons, making option B the defining characteristic of alkanes and the correct answer.