Final answer:
Marijuana is most commonly categorized as a hallucinogen due to its ability to alter sensory and perceptual experiences.
Step-by-step explanation:
The question relates to the classification of marijuana among psychoactive drugs and which category it falls into based on its pharmacological effects. While the classification can be complex due to drugs often having multiple effects, marijuana is most commonly classified as a hallucinogen. This classification is based on marijuana's potential to cause profound alterations in sensory and perceptual experiences, which can include perceptual anomalies and mild visual hallucinations.