Which type of hydrocarbon consists only of single covalent C-C bonds?

The correct choice is based on the structural characteristics of hydrocarbons. An alkane is defined as a saturated hydrocarbon, meaning it contains only single covalent bonds between carbon atoms (C-C bonds). This structure allows for maximum hydrogen saturation, hence the general formula for alkanes is CnH2n+2, where 'n' is the number of carbon atoms.

Other types of hydrocarbons differ in their bonding. Alkenes contain at least one double bond (C=C), while alkynes are characterized by at least one triple bond (C≡C). Cycloalkanes also consist of single C-C bonds; however, they form a cyclic structure. Despite the presence of single bonds, their cyclic nature distinguishes them from linear alkanes. Therefore, although cycloalkanes have single bonds, the option that specifically refers to hydrocarbons consisting entirely of single covalent C-C bonds in a linear or branched form is indeed the alkane.