What is a primary safety concern when driving under the influence?

Driving under the influence often significantly impairs a person's physical and mental capabilities, and decreased reaction time is one of the most critical safety concerns in such situations. Alcohol and drugs can slow the central nervous system, impacting a driver’s ability to respond quickly to changing conditions on the road, such as sudden stops, obstacles, or other vehicles. This delayed response can lead to serious accidents, as the driver may not be able to react in time to prevent a collision.

In contrast, the other options present situations that do not align with the effects of driving under the influence. Increased driving speed could occur in some cases, but it is not a direct result of impairment; rather, it often reflects a reckless attitude, which is distinct from the capacity to respond to driving situations. Better judgment is a misconception, as impairments typically lead to poor decision-making. Lastly, certain sobriety at night contradicts the premise of driving under the influence, as sobriety suggests a lack of impairment. These considerations highlight why decreased reaction time is the primary safety concern.