Answer:
b. are derived from opium
Explanation:
Morphine, heroin, and methadone are the name of drugs which are derived from the same source called opium poppy.
Morphine, heroin, and methadone are the class of drugs known as opioids or narcotic are used in medical treatment which interacts with brain to reduce pain perception and methadone is also used to reduces withdrawal symptoms due to addiction of heroin and morphine.
Hence, the correct answer is b.
