What type of functional group identifies an organic compound as an alcohol?

An organic compound is identified as an alcohol when it contains a hydroxyl group, which is represented as -OH. This functional group consists of an oxygen atom bonded to a hydrogen atom, and it is responsible for the characteristic properties of alcohols, including their ability to form hydrogen bonds, which influence melting and boiling points. Alcohols are generally characterized by their solvent properties, reactivity in certain types of chemical reactions, and their presence in many biological systems.

The other options do not specifically denote the presence of an alcohol functional group. For example, -CHO represents an aldehyde functional group, while C-C indicates a simple carbon-carbon bond, which can be found in many different types of organic compounds but does not signify an alcohol. A C-C triple bond indicates an alkyne, which is also a different category of organic compounds. Thus, the presence of the -OH group is the definitive feature distinguishing alcohols from other organic compounds.