Which of the following is a sign of impaired driving?

Answer: B — Swerving between lanes

Swerving between lanes is a clear indicator of impaired driving because it suggests that the driver is having difficulty maintaining control of their vehicle. This erratic behavior can result from various impairments, including alcohol or drug influence, fatigue, or distractions. When a driver swerves, they may be struggling to stay focused on the road, demonstrating a lack of coordination and awareness that are critical for safe driving. In contrast, driving under the speed limit or maintaining a steady speed can be done responsibly and may not necessarily imply impairment. Similarly, using turn signals properly is a sign of a conscientious driver who is following the rules of the road, further emphasizing that swerving is an unusual and concerning behavior that tends to indicate a problem.