When alcohol concentration reaches _____ of a person's blood by volume, that individual has reached a state of intoxication.

• A. 0.09 percent
• B. 0.05 percent
• C. 0.08 percent
• D. 0.10 percent

Answer: (A)

Blood alcohol concentration is the percentage of alcohol in the bloodstream, and as it rises, impairment increases. At about 0.09 percent, most people show clear signs of intoxication—impaired coordination, slower reaction times, reduced judgment, and difficulty concentrating. This level is often used in psychology and pharmacology to indicate that intoxication is present, sitting just above the common legal driving limit of 0.08 percent in many places. The other values correspond to milder impairment (0.05%) or higher thresholds used in different contexts (0.10%), but 0.09 percent is the point at which intoxication is generally recognized.