What defines a "controlled substance"?

A controlled substance is defined primarily by its potential for abuse and the associated risks it poses to individuals and society. Drugs classified as controlled substances are regulated under laws because they have a significant likelihood of being misused and may lead to physical or psychological dependence. This classification helps in monitoring and controlling their distribution and use.

Drugs with high potential for abuse are categorized into schedules under the Controlled Substances Act, which impacts their prescribing, dispensing, and use in medical practice. The scheduling system reflects the drug's accepted medical use, potential for abuse, and safety or dependence liability. This means that a controlled substance can be a medication used in healthcare that requires careful oversight due to its inherent risks, making option C the defining characteristic of a controlled substance.