Which of the following is an example of a drug that blocks the reuptake of both serotonin and norepinephrine into cells in the brain?

A. Venlafaxine (Effexor): Venlafaxine is a serotonin-norepinephrine reuptake inhibitor (SNRI) that increases the availability of both serotonin and norepinephrine in the synaptic cleft. By blocking reuptake, it enhances neurotransmission, which contributes to its antidepressant and anxiolytic effects. B. Diazepam (Valium): Diazepam is a benzodiazepine that enhances GABAergic neurotransmission, producing anxiolytic, sedative, and muscle-relaxant effects. It does not affect serotonin or norepinephrine reuptake and is not classified as an antidepressant. C. Phenelzine (Nardil): Phenelzine is a monoamine oxidase inhibitor (MAOI) that prevents the breakdown of monoamines, including serotonin, norepinephrine, and dopamine. It works via enzyme inhibition rather than reuptake blockade. D. Citalopram (Celexa): Citalopram is a selective serotonin reuptake inhibitor (SSRI) that specifically blocks serotonin reuptake without significantly affecting norepinephrine. Its mechanism is limited to serotonergic modulation.