Final answer:
Options a, b, and c all contain a benzene ring and thus can be classified as aromatic compounds, with benzene being the simplest example.
Step-by-step explanation:
The student asked which of the following organic compounds can be classified as aromatic: a. 2-phenyloctane b. 1,2-diethyl-5-methylbenzene c. benzene d. None of these. The definition of an aromatic compound is one that contains a benzene ring, which is a ring structure with alternating single and double bonds and a formula of C6H6. Options a, b, and c all contain a benzene ring, therefore they can be considered aromatic. Specifically, 2-phenyloctane has a benzene ring with an octane chain attached to it, 1,2-diethyl-5-methylbenzene has a benzene ring with ethyl and methyl groups as substituents, and benzene itself is the simplest aromatic compound.