What factors influence a person's blood alcohol concentration (BAC)?

The factors that influence a person's blood alcohol concentration (BAC) primarily include the amount of alcohol consumed and body weight. When a person drinks alcohol, the total amount ingested is a direct contributor to how much alcohol enters the bloodstream. The more alcohol consumed, the higher the BAC will be.

Body weight plays a critical role because it affects how alcohol is distributed in the body. Generally, individuals with a higher body weight may have a lower BAC than lighter individuals after consuming the same amount of alcohol, as there is more body mass to absorb the alcohol. Hence, both the volume of alcohol ingested and the person’s weight are fundamental in determining BAC levels.

The other choices do not directly impact BAC in the same fundamental manner. Levels of hydration and exercise frequency can influence how the body metabolizes alcohol, but they are not primary factors in determining BAC itself. The time of day and weather conditions do not impact how alcohol behaves in the body regarding absorption or metabolism. Additionally, while different brands of alcohol may vary in alcohol content, the brand itself is not a significant determinant of BAC—what matters more is the volume and concentration of alcohol consumed.