Which of the following behaviors might suggest an individual is under the influence of narcotics?

Facial itching is a common side effect associated with narcotic use. Narcotics can lead to various physiological reactions in the body, including itching sensations, often due to the way these substances affect histamine levels and opioid receptors. Individuals under the influence of narcotics may experience this facial itching as their body responds to the drug. Additionally, narcotics can lead to changes in mental state and physical sensations, contributing to this symptom.

The other choices represent behaviors or feelings that are less typical of narcotic influence. For instance, heightened awareness and extreme euphoria might be indicative of stimulant use rather than the sedative effects commonly associated with narcotics. Slight agitation could also be linked to different substances or withdrawal symptoms rather than being a direct indicator of narcotic intoxication. Therefore, facial itching stands out as a characteristic sign of narcotic influence.