Correct answer is (c) Fentanyl
The explanation is: Fully synthetic opioids are such as fentanyl, methadone, etc. These are fully made in the laboratories by the researchers. Most of them are made by mimicking the existing structures. Natural opiates are alkaloid contained in the resin of the opium poppy including morphine and codeine. Semi-synthetic opiates are created from natural opiates such as hydromorphone, oxycodone, and diacetylmorphine.