Final answer:
The legal Blood Alcohol Concentration (BAC) limit for individuals under the age of 21 is 0.02% or higher.
Step-by-step explanation:
The legal Blood Alcohol Concentration (BAC) limit for individuals under the age of 21 varies by country and state. In the United States, it is illegal for individuals under the age of 21 to operate a vehicle with a BAC of 0.02% or higher. If a person under 21 is found to have a BAC at or above this limit, they can be arrested for driving under the influence of alcohol.