Which of the following are common signs of alcohol impairment?

Swerving, going too fast or too slow are common signs of alcohol impairment because they indicate a loss of control over vehicle operation and an inability to maintain appropriate speed or lane discipline. When a driver is under the influence of alcohol, their coordination, reaction times, and judgment are significantly impaired, which can lead to erratic driving patterns such as swerving across lanes or fluctuating speeds that are not consistent with traffic conditions. These behaviors are clear indicators that a driver may be unable to operate a vehicle safely, increasing the risk of accidents.

While the other choices involve unsafe driving behaviors, they do not singularly indicate alcohol impairment as explicitly as the swerving and speed inconsistencies do. For example, driving without lights at night may occur for various reasons unrelated to alcohol, such as mechanical failure or forgetfulness, and using turn signals incorrectly can sometimes indicate a lack of attention rather than impairment. Overly compliant behavior may reflect different psychological states or personality traits rather than a clear indication of alcohol impairment.