Methadone is a(n) ______ & _____ treatment for _____ abuse, that works as an _____ for _____ receptors.

a) Effective, long-term, opioid, agonist, opioid
b) Controversial, short-term, stimulant, antagonist, dopamine
c) Common, temporary, alcohol, inhibitor, serotonin
d) Experimental, chronic, marijuana, blocker, cannabinoid