Answer:
Option c==> dopamine.
Explanation:
Dopamine is one of the chemicals known as the neurotransmitter which helps in the conveyance or transportation of information or signals and neurotransmitters also regulates mood and so on. The types of neurotransmitters are the options given in the question as options 'a' to 'd' that is to say, acetylcholine, GABA, dopamine and serotonin.
When people use stimulant, they wish to stay happy, that is to have the feelings of happiness longer and dopamine function is that. Dopamine contribute to the feelings of pleasure and happiness, so when stimul drugs are used they prolong the effects of of the neurotransmitter -- dopamine.
