How is Alcohol Concentration (A/C) expressed?

Alcohol concentration (A/C) is expressed in specific scientific measurements that provide an accurate assessment of the amount of alcohol present in the body. Specifically, it is quantified as grams of alcohol per 100 milliliters of blood or grams per 210 liters of breath. This method ensures a standardized and consistent measure that law enforcement and medical professionals can rely on when determining a person's level of intoxication.

In a legal context, particularly in the enforcement of motor vehicle laws, understanding and accurately measuring A/C is crucial because it directly relates to a person's ability to operate a vehicle safely. The levels defined by state laws often establish thresholds for driving under the influence (DUI) or driving while impaired (DWI).

Other options, while they pertain to alcohol in some context, do not accurately represent how blood alcohol concentration is measured in regulatory terms. Specifically, the choice regarding proof refers to a scale that relates to the alcohol volume but does not provide the precise quantification necessary for legal assessments. Similarly, expressing A/C in terms of liters per 1,000 liters of water is not a standard measurement related to human blood or breath alcohol testing practices. The first option, indicating percentage by volume, is more relevant for beverage alcohol but does not apply to the