Question

drugs that combat depression by affecting the levels or activity of neurotransmitters
amobarbitals
olanzapines
alprazolams
bupropions
antidepressants

Explanation:

Antidepressants are drugs that combat depression by affecting neurotransmitter levels or activity. Amobarbitals are barbiturates (sedatives/hypnotics). Olanzapines are antipsychotics. Alprazolams are benzodiazepines (anxiolytics). Bupropions are a type of antidepressant, but the general class of drugs described is antidepressants.

Answer:

antidepressants