Final answer:
The correct answer is that those under the legal drinking age should completely abstain from alcohol use, as should individuals who cannot practice moderation.
Step-by-step explanation:
Among the populations that should completely abstain from alcohol use, the most accurate answer is those under the legal drinking age. It is essential for individuals to follow the law, which usually determines the legal drinking age to protect young people from the premature consumption of alcohol and its potential harm to developing brains and bodies. Moreover, alcohol should be avoided by people who have difficulty controlling their consumption, known as individuals who cannot practice moderation. While having a first-degree relative with alcoholism may increase one's risk for developing alcohol-related problems, it does not necessitate complete abstinence unless the individual also struggles with moderation or alcohol abuse.