BAC stands for Blood Alcohol Concentration- the measure for the amount of alcohol in person’s blood stream. The key factors that can influence BAC are:
1. the alcohol itself (content and amount)
2. gender (females have higher BAC than males)
3. weight (the less the weight, the more alcohol consumption will affect the body and BAC)
4. food intake
5. duration (the faster the consume of alcohol, the higher the BAC)
From all above, a the first one : content of the alcohol and how much a person has drunk influences BAC the most.