Which of the following could indicate a student is under the influence of drugs?

Reddish, puffy eyes can be a significant indicator that a student may be under the influence of drugs. Many substances, including marijuana and some prescription medications, can cause blood vessels in the eyes to dilate, leading to a characteristic red appearance. Additionally, the puffiness may result from various factors related to drug use, such as dehydration or allergic reactions frequently associated with certain substances.

In contrast, the other options do not typically align with signs of drug influence. For example, focused and articulate speech, maintaining eye contact, and a stable gait are often associated with sober behavior and cognitive function. These characteristics suggest that an individual is likely functioning normally, which stands in stark contrast to the physical signs often related to drug impairment. Hence, the presence of reddish, puffy eyes stands out as a clear potential red flag for drug influence in a student.