What must alkynes contain?

Alkynes are defined as hydrocarbons that contain at least one carbon-carbon triple bond. This characteristic is what distinguishes them from other types of hydrocarbons, such as alkenes, which contain double bonds, and alkanes, which contain only single bonds. The presence of a triple bond in alkynes leads to unique chemical properties and reactivity, making them an important class of compounds in organic chemistry.

In the context of the other options, double bonds would classify a compound as an alkene, and having no double or triple bonds would describe alkanes. Additionally, two single bonds do not provide the structural definition necessary to categorize any hydrocarbons specifically. Thus, the presence of one triple bond is the correct defining feature of alkynes.