Which of the following is NOT an example of a drug source?

The option indicating humans is correct because humans are not traditionally considered a source of drugs in the same way that plants, animals, and minerals are.

Plants are a well-known source of numerous pharmaceutical compounds; for example, many medicinal drugs are derived from plant alkaloids and other phytochemicals. Animals contribute to drug sources as well, with hormones, enzymes, and antibodies sourced from various animal tissues used in medications. Minerals, such as salts and metals, are also integral to the creation of certain drugs, serving various therapeutic roles.

In contrast, while humans may produce substances that can be utilized in medicine (such as insulin), they are not classified as a drug source in the way the other categories are. This distinction emphasizes the traditional categories from which drugs are derived in pharmacology.