Which of the following is a sign that a person may be under the influence of drugs or alcohol?

The presence of erratic behavior, slurred speech, and difficulties with coordination serves as significant indicators that a person may be under the influence of drugs or alcohol. When individuals consume substances that impair their cognitive and physical abilities, these symptoms often manifest. Erratic behavior can include unpredictable movements or actions that don't align with a person's usual demeanor, indicating a possible neurological impact from substance use. Slurred speech reflects impaired motor function and communication abilities, which are common effects of alcohol intoxication and certain drugs. Additionally, difficulties with coordination suggest that the individual's ability to manage their physical movements has been compromised, further corroborating the likelihood of substance influence.

In contrast, calm demeanor and clear speech would typically suggest that a person is sober and functioning normally. Consistent focus and stability also indicate normal cognitive and physical function, while heightened awareness and alertness can be typical of an individual who is sober and engaged, rather than under the influence. Thus, the characteristics outlined in the correct option directly align with the recognized signs of impairment due to drug or alcohol use.