Which term best matches the description "Substance altering body function"?

• A. Drug
• B. Food and Drug Administration (FDA)
• C. Drug Enforcement Administration (DEA)
• D. Bioequivalence

Answer: (A)

A drug is any chemical substance that, when introduced into the body, alters its function or physiology. This broad definition captures substances that produce therapeutic effects as well as those that change bodily processes in other ways. In pharmacology, the term refers to anything that can influence body systems, whether used to diagnose, treat, or prevent disease, or simply affect normal physiology.

The other options are not substances: the FDA and DEA are regulatory agencies that oversee drug development, approval, scheduling, and enforcement; bioequivalence is a concept used to compare two drug products to ensure they deliver the same amount of active ingredient into the body at the same rate, not a substance itself.