Final answer:
The schedule with the highest risk of abuse potential among the options given is Schedule C2. It includes drugs with a high potential for abuse and may have accepted medical uses but with severe restrictions. Examples of drugs in this category are heroin, morphine, and oxycodone.
Step-by-step explanation:
The schedule of controlled substances that has the highest risk of abuse potential is Schedule C2. In the United States, substances that have a high potential for abuse and dependency are classified under five schedules (I-V) as part of the Controlled Substances Act, with Schedule I being the category reserved for the most dangerous drugs with no accepted medical use and a high potential for abuse. Since the question asks about Schedule C2 (Schedule II), it implies that we are looking at the next level of controlled substances which have a high potential for abuse but may have some accepted medical use with severe restrictions. Drugs in this category include opiates such as heroin, morphine, and oxycodone, as well as other prescription pain relievers.