Which cognitive or physical ability is impaired EARLIEST as BAC begins to rise, even at 0.02-0.04%?

Explanation

Even low BACs (0.02-0.04%) impair the brain's executive functions: judgment, risk assessment, social inhibition, and divided attention. This is why patrons become louder, more talkative, and willing to order another round long before they slur or stumble. By the time gross motor coordination (a) and clear slurring (b) appear, BAC is typically 0.10% or higher. Server intervention is most effective in the early stages, before judgment is fully compromised.