Final answer:
Amphetamines are the class of drugs often abused for alertness and euphoria. Other options, such as Alcohol, Barbiturates, and Benzodiazepines, generally have sedative effects.
Step-by-step explanation:
The class of drugs commonly abused to produce alertness and euphoria is Amphetamines (D). Amphetamines are central nervous system stimulants that can increase energy and concentration while providing feelings of well-being, making them prone to misuse. In contrast, Alcohol tends to depress the central nervous system, and both Barbiturates and Benzodiazepines are typically used as sedatives or to treat anxiety, rather than increase alertness or euphoria.