Most drugs of abuse flood the circuits of the reward center in the brain with ; some drugs also reduce the level of after long term use and causes .

feeling of pleasure, dopamine, tolerance

Explanation:

Drugs of abuse causes the brain to produce neurotransmitters called dopamine, this neurotransmitter produces a sense of pleasure. The constant intake of drugs increases the tolerance of drug and the body requires more dose so as to experience the desired effect. Drug abuser may need more amount of drug than before to experience the same level of dopamine to get high.

answer; i do believe that the correct answer is (punch card ballots);

51% were unhappy, i think .   ; )