Which of the following drugs is listed under MRB II?

• A. Cocaine
• B. Ketamine
• C. Fentanyl
• D. LSD

Answer: (C)

MRB II is a risk-based category used here to group substances that have legitimate medical use but carry high potential for abuse and safety concerns. Fentanyl fits that profile because it is an extremely potent synthetic opioid with a high risk of misuse, overdose, and diversion, so it’s placed in MRB II to reflect the need for tighter controls. The other drugs have different risk or regulatory profiles in this framework: LSD is typically treated as a highly restricted substance with little or no medical use, ketamine is controlled but used medically and falls into a different tier, and cocaine, while also tightly controlled, is assigned to other categories based on its specific risk and medical-use considerations. So fentanyl is the correct choice for MRB II.