What is the structure of a phenol?

The structure of a phenol is characterized by the presence of a benzene ring, which is a six-membered carbon ring with alternating double bonds, and a hydroxyl group (-OH) attached directly to one of the carbon atoms of the ring. This specific structure is what defines phenol and distinguishes it from other types of organic compounds. The hydroxyl group imparts acidic properties and influences the chemical behavior of phenol, making it an important compound in organic chemistry.

The other options describe different structures. A carbon chain with carboxylic acids would represent fatty acids or other carboxylic acids, which lack the aromatic nature of phenols. A molecule containing multiple double bonds could refer to alkenes or polyenes but does not specifically indicate the presence of a benzene ring or a hydroxyl group. Lastly, a saturated hydrocarbon contains only single bonds between carbon atoms and does not feature a benzene structure or a hydroxyl functional group.