Final answer:
An adult drinking alcohol for pleasure is an example of legal recreational use, where consumption is legal within the boundaries of law for adults and intended for social and euphoric experiences.
Step-by-step explanation:
An adult drinking alcohol to feel pleasant is an example of c) legal recreational use. This refers to the consumption of substances like alcohol for enjoyment and social interaction, which is legal for adults in many jurisdictions, as long as it is done within the limits of the law. Recreational use implies that the substance is being used not for medical purposes but rather for creating a feeling of euphoria or enhancing social experiences. While some psychoactive drugs, such as cannabis, may have varying legal statuses, alcohol remains a legal substance for recreational use in most places, provided the individual consuming it is of legal drinking age.