Final answer:
Amphetamine is the drug that is not found in nature or derived from natural substances, as opposed to nicotine, THC, and cocaine, which are all naturally occurring.
Step-by-step explanation:
The drug that is not found in nature or derived from natural substances is C) Amphetamine. While nicotine, delta-9-tetrahydrocannabinol (THC), and cocaine are all found in nature and derived from plants, amphetamine is a synthetic substance. Cocaine is extracted from the leaves of the coca plant, nicotine is a constituent of tobacco, and THC is the active compound found in cannabis. In contrast, amphetamine is a synthetic drug and doesn't occur naturally. It is a stimulant that increases levels of neural activity and has a high potential for abuse and addiction.