What drugs are examples of second-line opioid agonists/antagonists prescribed for the treatment of moderate-to-severe pain? select all that apply?

The answer should be: codeine, hydrocodone, oxycodone or tramadol

Opioid drugs are frequently used to treat pain. Acetaminophen, aspirin or NSAIDs drug used for mild to moderate pain. The mild opioid will be used in moderate to severe pain while a strong opioid will be used in severe pain. Strong opioid that could be used for severe pain would be morphine, methadone, oxycodone, or fentanyl

The littoral zone. . .

The reactants are co_{2} aka carbon dioxide and h_{2}o aka water along with light energy