Support for the hypothesis that deficiencies in monoaminergic neuronal systems result in depression come from observations that

a. reserpine, which can reduce monoamine levels in the brain, may induce symptoms of depression.
b. the time-course of symptom remission in depressed individuals treated with most antidepressants correlates almost perfectly with the time-course of these drugs' pharmacodynamic actions of inhibiting serotonin or norepinephrine reuptake or inhibiting monoamine oxidase activity.
c. virtually all healthy adults, i.e., those with no history of depression personally or within their family, will exhibit the core symptoms of depression upon being administered treatments that reduce the levels of serotonin or norepinephrine in the brain.
d. all of these

a