A person showing which of the following signs may be influenced by cannabis?

A person influenced by cannabis may exhibit body tremors. Cannabis can affect the central nervous system and lead to physical symptoms such as tremors or shakes. These physiological responses can indicate intoxication, as cannabis can alter motor functions and coordination. While cannabis influences a person's cognitive and physical abilities, body tremors are a specific physical sign that can arise from its use.

Other options typically do not correlate with cannabis influence. For instance, extreme alertness is more commonly associated with stimulants rather than the depressant effects characteristic of cannabis. Improved coordination and sharp memory retention are also not typical, as cannabis often impairs motor skills and memory as part of its psychoactive effects. Therefore, body tremors serve as a more accurate indicator of cannabis influence.