Final answer:
Methane, ethane, propane, and butane are alkanes; ethylene is an alkene; and acetylene is an alkyne. These compounds are categories of hydrocarbons distinguished by their bonds: single, double, or triple covalent bonds between carbon atoms.
Step-by-step explanation:
Methane, acetylene, ethane, ethylene, propane, and butane are all types of hydrocarbons. Specifically, methane, ethane, propane, and butane are alkanes, which are aliphatic hydrocarbons with only single covalent bonds. Ethylene is an example of an alkene, which contains at least one C-C double bond. Acetylene falls into the category of alkynes, characterized by a C-C triple bond. Therefore, methane, ethane, propane, and butane are classified as alkanes (Option A), ethylene as an alkene (Option B), and acetylene as an alkyne (Option C). None of these are aromatics (Option D), which are compounds containing a benzene ring.