Final answer:
Zolpidem is a central nervous system agent used to treat insomnia, while benzodiazepines like Alprazolam and Diazepam are used to treat anxiety, both acting as GABA agonists.
Step-by-step explanation:
The central nervous system agent used to treat anxiety and/or insomnia from the options provided is d. zolpidem. Zolpidem is a sedative-hypnotic drug that calms the brain and helps to induce sleep, making it effective in treating insomnia. In contrast to Zolpidem, other central nervous system agents such as benzodiazepines, which include Alprazolam, Diazepam, and Lorazepam, are commonly prescribed to reduce symptoms of anxiety.
They act as GABA agonists, enhancing the neurotransmitter's quieting effect on the brain, which in turn decreases anxiety, induces sedation, or helps in muscle relaxation. These medications should be used as prescribed, considering the risk of dependence, especially when treating insomnia.