Which of the following substances can impair driving ability?

Driving ability can be impaired by a variety of substances, including prescription medications and illegal drugs. Prescription medications, even when taken as directed, can have side effects such as drowsiness, dizziness, or impaired coordination, all of which can negatively affect a person's ability to focus and respond while driving. Illegal substances, on the other hand, can cause severe impairments, including altered judgment, reduced reaction times, and distorted perceptions of reality, which can lead to unsafe driving.

The other options are limited in scope. While alcohol is a well-known impairing substance, it is not the only one, which is why the choice focusing solely on alcohol does not encompass the full range of impairing substances. Illegal drugs are not the sole category of substances that can impair driving, as prescription medications also pose significant risks. Caffeine and energy drinks, while they may have some stimulating effects, typically do not lead to impairment in the same way that prescription drugs or illegal substances can. Therefore, prescription medications and illegal substances collectively cover a broader and more impactful range of impairments relevant to driving safety.