Which of the following is a sign of cocaine use?

Restlessness is a well-documented sign of cocaine use due to the stimulant effects of the drug. Cocaine increases levels of dopamine, a neurotransmitter associated with pleasure and reward, which heightens arousal and energy levels. This heightened state can lead to an inability to stay still, resulting in restlessness or agitation as individuals may experience increased energy and a compulsion to move around.

Other physical and psychological symptoms often associated with cocaine use could include paranoia, anxiety, and increased heart rate, all of which can contribute to a sensation of restlessness. In contrast, the other options do not typically correlate with cocaine use. For example, weight gain is more commonly associated with other conditions or the use of substances that suppress metabolism rather than stimulants like cocaine. Diarrhea, while it can be a side effect of various substances, is not a direct indicator of cocaine use. Muscle weakness may result from various other health issues rather than the use of stimulants such as cocaine.