Which of the following is an example of an aromatic hydrocarbon?

Benzene is the correct example of an aromatic hydrocarbon due to its unique structure and properties. Aromatic hydrocarbons are characterized by having a planar ring of carbon atoms bonded in a manner that includes alternating single and double bonds, which results in resonance stability. This specific arrangement allows for delocalized electrons across the ring, giving aromatic compounds distinct chemical stability and reactivity compared to non-aromatic hydrocarbons.

Benzene, specifically, consists of six carbon atoms arranged in a hexagonal ring, with each carbon atom bonded to a hydrogen atom. The resonance between the double bonds means that the actual structure is a hybrid of multiple forms, leading to a stable compound with equal bond lengths. This stability is what distinguishes aromatic hydrocarbons and makes them a significant category in organic chemistry.

In contrast, methane, hexane, and propane are examples of aliphatic hydrocarbons. They do not possess the resonance structures or cyclic arrangements that characterize aromatic compounds, making them fundamentally different in both structure and chemical behavior. Thus, benzene stands out as the quintessential example of an aromatic hydrocarbon within the given choices.