Which definition describes psychoactive drugs?
a. drugs that act as sedatives and slow down activity and make a person calm, sleepy, or even unconscious
b. drugs that are derived from opium as well as drugs that have similar chemicals but are man-made
c. drugs that energize behavior and are often used to help a person stay awake, lose weight, or elevate mood
d. drugs that have chemicals that influence perceptions, moods, consciousness, or behavior