Answer:
psychoactive
Step-by-step explanation:
Opiod are the drugs that are used to relieve pain. Narcotic are the drugs that are similar to opiods which affect moods and also behavior. Barbiturate are the drugs which are mostly used to relax body and also treat seizures. Psychoactive drugs are the drugs which cause changes in brain in terms of perception, mood, and behavior.
Caffeine is stimulant for central nervous system. It belongs to the methylxanthine class.
It is legal and also it is the world's most consumed psychoactive drug.