d none of hte above.
to my understanding heroin is a drug, but nicotine is a chemical ???
i could be fecking wrong on this.
but i am aware that nicotine is the most widely consumed 'thing' and most addictive on earth.
heroin closely follows 2nd as most addictive substance to man.
caffeine might not be too far off, and acohol too.
'Nicotine serves as the tobacco plant’s natural defense against insects and, in its pure form, is more poisonous than either strychnine or arsenic. Its chemical structure is similar to acetylcholine, a neurotransmitter, giving it easy access to the brain’s reward and pleasure pathways. '