Place the following opioids: oxycodone, fentanyl, hydrocodone, hydromorphone in order of their relative potency - highest to lowest.
A) Fentanyl > Hydromorphone > Oxycodone > Hydrocodone
B) Fentanyl > Oxycodone > Hydromorphone > Hydrocodone
C) Hydromorphone > Fentanyl > Oxycodone > Hydrocodone
D) Oxycodone > Fentanyl > Hydromorphone > Hydrocodone