Which of the Following Is the Best Definition of a Psychoactive

Multiple Choice

Which of the following is the best definition of a psychoactive drug?

A) a drug produced by the brain in order to stimulate sensory experiences in the visual system
B) any substance which has been declared illegal for use or for use without a prescription
C) chemicals which affect the nervous system, resulting in altered consciousness and perceptions
D) neurotransmitters which, when released, change the behavior of an individual