The class of drug that increases the activity of the central nervous system is known as:
stimulants
narcotics
hallucinogens
depressants

Stimulant drugs increase the activity of the central nervous system.

Explanation:

Depressants reduce the activity of the central nervous system.

Hallucinogens are psychoactive drugs which impact impact the central nervous system by altering perception.

Narcotics impact the central nervous system by working to reduce the perception of pain. Narcotics are classified as depressants.

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