Which illegal substance is derived from the cannabis plant?

The correct answer is cannabis, which is indeed derived from the cannabis plant. This plant produces various compounds known as cannabinoids, the most notable of which are tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the psychoactive component responsible for the "high" associated with cannabis use. Cannabis can be consumed in various forms, including dried flowers, oils, and edibles, and is widely recognized for both its recreational and medicinal uses, though it remains illegal in many areas.

Mushrooms, cocaine, and opium, while they are popular substances that may be associated with illegal drug use, originate from entirely different sources. Mushrooms refer to psilocybin mushrooms which are not derived from the cannabis plant, cocaine comes from the coca plant, and opium is obtained from the poppy plant. Thus, understanding the origin of these substances clarifies why cannabis is the only option related to the cannabis plant itself.