What does the term "controlled substance" refer to?

The term "controlled substance" refers to a drug that is regulated by law due to its potential for abuse and dependency. This classification is essential in the context of pharmacology and law, as it helps to prevent misuse and ensures that these substances are prescribed and dispensed appropriately. Controlled substances are categorized into schedules based on their risk of addiction and therapeutic value, with stricter regulations applied to those with higher potential for abuse.

In contrast, the other options do not capture the essence of what a controlled substance is. Medications available without a prescription are typically not considered controlled substances, while nutritional supplements are not classified as drugs under this terminology and do not fall under the same regulatory frameworks. Likewise, a medication with no therapeutic use does not align with the concept of controlled substances, as it implies a lack of regulation based on potential for abuse or therapeutic value. Thus, the focus on the potential for abuse and legal regulation makes the first choice the correct understanding of a controlled substance.