What is a potential effect of stimulant drugs on mental tasks?

Stimulant drugs are known to increase the levels of certain neurotransmitters in the brain, such as dopamine and norepinephrine, which play key roles in attention, motivation, and arousal. As a result, one of the main effects of stimulants is enhanced focus and energy, particularly when performing mental tasks. This increased stimulation can lead to improved performance on tasks that require attention and cognitive effort, making it easier to concentrate and stay engaged.

While other options suggest effects such as relaxation, decreased alertness, or fatigue, these do not align with the known properties of stimulant drugs, which are actually characterized by their ability to heighten arousal and cognitive engagement. Therefore, the enhancement of focus and energy is the most accurate representation of the effects associated with stimulant use.