Which of the following factors is NOT a main contributor to an individual's BAC?

Age is not considered a main contributor to an individual’s Blood Alcohol Concentration (BAC). While age can influence how alcohol affects a person due to various physiological changes that occur as people grow older, the primary factors affecting BAC are more directly related to physiological attributes and consumption patterns.

Rate of consumption plays a significant role, as drinking alcohol quickly increases BAC more rapidly than drinking slowly. Gender affects how alcohol is metabolized due to differences in body composition, such as the proportion of body water and fat, which influences how alcohol is absorbed and processed. Weight is also a crucial factor since individuals with lower body weight generally have a higher BAC than heavier individuals after consuming the same amount of alcohol, primarily because of differences in body water volume.

In summary, while age can have some effect on alcohol tolerance and metabolism, it is not one of the main physical factors that directly contribute to the calculation of BAC compared to the rate of consumption, gender, and weight.