Amphetamines​

A) ​are stimulants.
B) ​are depressants.
C) ​include opium and marijuana.
D) ​include barbiturates and tranquilizers.

Amphetamines

A class of stimulant drugs that increase activity in the brain and have effects such as increased energy and alertness.

Barbiturates

A class of drugs that act as central nervous system depressants and are used for various medical purposes including as sedatives, anxiolytics, and anticonvulsants.

Tranquilizers

Medications used to reduce tension or anxiety, working by depressing the central nervous system.