Which of the following are Schedule II controlled substances?

Schedule II controlled substances are drugs that have a high potential for abuse, which may lead to severe psychological or physical dependence. They are considered to have legitimate medical uses but are strictly regulated due to their potential for addiction and misuse.

Morphine tablets are classified as a Schedule II substance because they are potent opioids used to treat severe pain and have a high potential for abuse. Similarly, fentanyl injections are also Schedule II controlled substances, as fentanyl is a powerful synthetic opioid that is used medically for pain management but is extremely potent and can lead to significant risks of overdose and addiction. Lastly, secobarbital capsules are included in this schedule due to their use as a central nervous system depressant for treating certain conditions, alongside their misuse risk.

Since all the listed substances share characteristics that qualify them for Schedule II status, the correct answer recognizes that morphine, fentanyl, and secobarbital are all classified within this category. Therefore, the selection that encompasses all these options is accurate, establishing the comprehensive understanding needed to categorize these substances appropriately.