What does a drug mean?

• A. A substance used for cleaning surfaces
• B. Any substance that can be sold over the counter
• C. Articles intended for diagnosis, cure, mitigation, treatment, or prevention of disease in humans or animals
• D. A vitamin supplement

Answer: (C)

In public health terms, a drug is defined by its intended use to diagnose, cure, mitigate, treat, or prevent disease in humans or animals. So the best choice captures that purpose-driven definition: if a product is marketed or used with claims to diagnose, treat, prevent, or cure disease, it falls under the category of a drug.

The other ideas don’t fit because cleaning substances are designed for surface cleanliness rather than disease treatment, merely being sold over the counter doesn’t make something a drug, and vitamins are typically viewed as dietary supplements rather than drugs unless they are marketed for disease treatment or prevention.