Answer: A. Modafinil
It is important to understand that the use of any currently available pharmaceutical agents to enhance cognition is off-label and is limited by evidence of efficacy. Modafinil is a wake-promoting agent that has been used for narcolepsy and was researched for use in ADHD. While the exact mechanism is unknown, modafinil may exert its effect by modulating GABA- and glutamate-mediated neurotransmission, thereby resulting in reuptake inhibition of dopamine and norepinephrine.
For more on this topic, see Cognitive Enhancers in Children and Adolescents: What Psychiatrists Need to Know, on which this quiz is based.