Final answer:
Measurable behavioral effects of alcohol start at a BAC level of 0.02%. Effects vary among individuals, but 0.08% is the legal limit for intoxication in most US states.
Step-by-step explanation:
The measurable behavioral effects of alcohol on a person can begin at a relatively low blood alcohol concentration (BAC) level. The correct answer to what BAC level begins to produce measurable behavioral effects is a. 0.02%. Even at this low concentration, individuals might experience some changes in mood and behavior. BAC levels above this can result in further impairment, and a BAC of 0.08% is generally considered to be the legal limit for intoxication in most US states. It is important to remember that these effects can vary between individuals based on a variety of factors including body size, tolerance to alcohol, and general health.