Which of the following conditions is least likely linked to an increased presence of beta waves on an EEG?

The presence of beta waves on an EEG is typically associated with alertness, active thinking, problem-solving, and various states of arousal. Stress and the use of psychoactive medications often lead to increased beta activity because these conditions can heighten cortical activity and arousal. Alcohol intoxication, on the other hand, may present with altered brain activity, but initially, it can also lead to increased beta waves due to its stimulant effects before depression sets in.

A relaxed mental state, in contrast, tends to be characterized by alpha waves, which are indicative of calmness and relaxation rather than active mental engagement. This state usually results in a reduced presence of beta waves. Therefore, the condition that is least likely linked to an increased presence of beta waves is a relaxed mental state, as it does not promote the same level of cognitive activity or arousal as the other conditions listed.