Four of the six major categories of controlled substances include narcotics, depressants, and:

• A. Hallucinogens
• B. Stimulants
• C. Inhalants
• D. Cannabinoids

Answer: (A)

There are six broad categories used to group controlled substances, each describing a different set of effects and risks. Narcotics and depressants are two of these categories, and the missing category in the trio described by the question is hallucinogens. Hallucinogens are substances that alter perception, mood, and thinking, with examples like LSD, psilocybin, and mescaline. They fit with narcotics and depressants as one of the major classes used in safety and law contexts. The other options—stimulants, cannabinoids, and inhalants—are each recognized as separate major categories, but they don’t complete the specific group highlighted in this item.