Which of the following behaviors might suggest that a driver is under the influence of drugs instead of alcohol?

The behavior indicative of a driver being under the influence of drugs often manifests as unusual behaviors, which can include mood swings, erratic actions, and a lack of coordination. Unlike alcohol, which typically produces more uniform symptoms such as slurred speech and impaired judgment, drug impairment can show a broader range of behavioral changes. For instance, a driver might exhibit sudden shifts in mood, anxiety, or hyperactivity, which are not typical signs of alcohol intoxication. Additionally, drugs can affect motor skills differently, leading to issues with coordination that might not be present in a driver impaired by alcohol. Recognizing these behaviors can be crucial for law enforcement when assessing a driver's level of impairment and deciding on the appropriate course of action during a traffic stop.

Other options reflect behaviors more commonly associated with alcohol intoxication (like slurred speech) or are neutral behaviors (like driving within speed limits), which do not provide a strong indication of drug use or impairment. Excessive laughter, while it might suggest intoxication, is less specific to drug use and can also occur under the influence of alcohol.