The most appropriate response by the nurse when a despondent patient says "Nothing matters anymore" would be:

Choice A reason: Exploring past interests is therapeutic but does not directly address the immediate suicide risk implied by hopelessness. Depression’s serotonin deficit heightens amygdala-driven despair, and assessing suicidal ideation is critical to prioritize safety over general exploration of interests. Choice B reason: Reassuring the patient about reasons to live is dismissive and risks alienating them. Hopelessness in depression reflects serotonin and prefrontal cortex dysregulation, and this response fails to assess suicide risk, missing critical amygdala-driven warning signs. Choice C reason: Asking about suicidal thoughts directly assesses risk, critical in depression with low serotonin and heightened amygdala activity driving hopelessness. This prioritizes safety, engaging prefrontal cortex reflection to identify immediate danger and guide intervention, making it the most appropriate response. Choice D reason: Encouraging hope is vague and does not assess suicide risk. Depression’s serotonin deficit and amygdala hyperactivity require direct evaluation of suicidal ideation, as hopelessness signals potential danger, making this response inadequate for ensuring patient safety.