Which of the following is an example of a Schedule I drug?

Heroin is classified as a Schedule I drug because it has a high potential for abuse, has no accepted medical use in treatment in the United States, and lacks accepted safety for use under medical supervision. Schedule I substances are deemed to have the most restrictive regulations due to their perceived dangers and lack of medicinal benefit.

In contrast, the other options represent drugs with accepted medical uses and varying levels of potential for abuse. Oxycontin is a controlled substance classified under Schedule II due to its potential for severe dependence and its medical uses for pain relief. Adderall falls under Schedule II as well, utilized for Attention Deficit Hyperactivity Disorder (ADHD) treatment, acknowledging its potential for abuse. Valium, used to treat anxiety, is classified under Schedule IV, indicating a lower potential for abuse compared to drugs in higher schedules. Thus, Heroin stands out as the only option that corresponds to Schedule I criteria.