Final answer:
The liver (option C) is the main organ involved in drug metabolism and is responsible for breaking down or modifying various substances, including drugs.
Step-by-step explanation:
The liver (option C) is the main organ involved in drug metabolism. It is responsible for breaking down or modifying various substances, including drugs, in a process called drug metabolism. The liver has enzymes that metabolize drugs into different compounds that can be excreted from the body. Other organs, such as the kidney, small intestine, and lungs, can also play a role in drug metabolism, but the liver is the primary site.