Which of the following is a monoamine oxidase inhibitor (MAOI)?

Nardil, which is the correct answer, is classified as a monoamine oxidase inhibitor (MAOI). MAOIs are a class of medications primarily used to treat depression by inhibiting the activity of monoamine oxidase enzymes in the brain. This inhibition leads to increased levels of neurotransmitters such as norepinephrine, serotonin, and dopamine, which can enhance mood and alleviate depressive symptoms.

Nardil, in particular, has a well-established history in the treatment of major depressive disorder, especially in cases where other treatments have been ineffective. The unique mechanism of action of MAOIs sets them apart from other classes of antidepressants, hence their specific therapeutic applications.

The other medications listed serve different purposes. Wellbutrin is an atypical antidepressant that primarily affects dopamine and norepinephrine reuptake. Elavil (amitriptyline) is a tricyclic antidepressant that works by inhibiting the reuptake of serotonin and norepinephrine. Prozac (fluoxetine) is a selective serotonin reuptake inhibitor (SSRI) that specifically targets serotonin levels. Each of these alternatives operates through different mechanisms and does not qualify as an MAOI.