What does blood alcohol concentration (BAC) measure?

Blood alcohol concentration (BAC) specifically measures the amount of alcohol present in a person's bloodstream, expressed as a percentage. This metric indicates how much of the blood's volume is composed of alcohol, quantifying it in terms of milligrams of alcohol per deciliter of blood. This measurement is crucial for understanding the degree of intoxication an individual may be experiencing, as BAC levels correlate with impairment and are often used in legal contexts regarding driving under the influence.

The other choices refer to different aspects of blood chemistry or alcohol metabolism, but they do not accurately describe BAC. For example, the percentage of blood sugar pertains to glucose levels, while the volume of alcohol in the bloodstream and the amount of alcohol metabolized per hour do not provide the specific measurement that BAC offers, which is a precise metric essential for assessing intoxication levels.