What is a drug?

• A. A chemical substance used to improve mood in beverages.
• B. A natural substance found in foods.
• C. A cosmetic product.
• D. A chemical substance that alters the physical, behavioral, psychological, or emotional state of the user.

Answer: (D)

A drug is any chemical substance that changes how the body or mind functions. The key idea is that the substance alters physical, behavioral, psychological, or emotional states in the user, not merely that it exists in a drink or a cosmetic product. This broad definition covers medicines, stimulants, depressants, and various other agents because what matters is the effect on state, not the context in which the substance is found.

The option about a chemical used to improve mood in beverages is too narrow because it focuses on a specific use and context rather than the fundamental effect on state. The one about a natural substance found in foods isn’t defining the essential action of a drug, since natural origin doesn’t determine whether something qualifies as a drug. The cosmetic product choice is off target because cosmetics are intended for appearance or skin care, not to alter the user’s internal state.