Which of the following controlled substances may not be refilled?

The correct choice is based on the regulations surrounding controlled substances, particularly the rules governing refills. In the context of New York pharmacy law, schedule II controlled substances (CII) are subject to strict regulations and cannot be refilled. This means that once a CII prescription is filled, a new prescription must be obtained from the prescriber for any additional supply.

Steroids and diazepam also fall under this categorization when related to their classification as controlled substances. In New York, anabolic steroids can be classified as a schedule III (CIII) controlled substance, which allows for refills under specific conditions. However, diazepam, as a benzodiazepine, is categorized as a schedule IV (CIV) controlled substance, which does allow for refills, provided it is done within the prescribed limits. Therefore, option C accurately groups substances according to their refill limitations, aligning with the regulation that CII substances cannot be refilled at all.

CII drugs represent the most restricted class due to their high potential for abuse and dependency, while CIII and CIV categories, although still controlled substances, have more lenient rules regarding refills. Thus, the combination of CII drugs with other specific substances that may not be refilled