All the major biological explanations related to drug abuse assume that these substances exert their effects by altering brain chemistry or neuronal (basic functional cell of the brain) activity.

Psychoactive

Explanation:

Psychoactive effects of drugs are capable of changing the mood, awareness and thoughts of the users/consumers.

Psychoactivity of drugs gives rise to change in the information exchanges between the cells of the brain.They are also able to copy the effects and behavior of neurotransmitters. This gives rise to continued dependence and addiction of such drugs.

Example of psychoactive drugs include cocaine, cannabis, alcohol etc

substitution is the answer in this case

option c is the correct answer.