The most principal psychoactive chemical in marijuana is:

• A. LSD
• B. PCP
• C. MDMA
• D. THC

Answer: (D)

The main psychoactive chemical in marijuana is delta-9-tetrahydrocannabinol, or THC. Cannabis contains several cannabinoids, but THC is the one most responsible for the drug’s psychoactive effects because it binds strongly to CB1 receptors in the brain, altering neurotransmitter release and changing perception, mood, memory, and coordination. This binding produces the familiar high, along with effects like altered time perception and increased appetite. The other substances mentioned are different drugs with distinct active compounds and mechanisms—LSD is a hallucinogen that largely affects serotonin receptors; PCP is a dissociative that disrupts glutamate signaling; MDMA increases serotonin and other neurotransmitters to produce stimulant-empathetic effects. They do not originate from cannabis and do not represent its principal psychoactive component.