Final answer:
The CNS effects of cannabis are mainly due to modulation of the endocannabinoid system, as cannabinoids such as THC interact with cannabinoid receptors, altering neurotransmitter release.
Step-by-step explanation:
The central nervous system (CNS) effects of cannabis are due mostly to C) Modulation of the endocannabinoid system. Cannabis contains active compounds called cannabinoids, which interact with a network of cannabinoid receptors and endogenous ligands known as endocannabinoids in the body. This system plays a key role in regulating a variety of physiological processes including appetite, pain sensation, mood, and memory.
Cannabinoids from cannabis, such as THC (tetrahydrocannabinol), bind to these receptors and can alter normal neurotransmitter release, thus affecting the CNS.