What are signs of a driver who may be impaired?

Signs of a driver who may be impaired typically include behaviors that deviate from safe and responsible driving practices. Weaving on the road can indicate loss of control or an inability to maintain a steady path. Erratic speed, whether speeding up or slowing down unexpectedly, suggests that the driver may not be fully aware of their surroundings or unable to make sound judgments about safe driving speeds. Running red lights is a significant indicator of impaired judgment or reduced reaction times, as stopping at traffic signals is a fundamental rule of safe driving.

In contrast, using turn signals frequently, maintaining consistent speed, and stopping at all traffic signs reflect responsible driving behavior and awareness of traffic laws. These behaviors do not suggest impairment and instead indicate that a driver is attentive and following road safety rules. Thus, option C accurately captures the signs of impairment that are a concern on the road.