Final answer:
The blood alcohol concentration (BAC) determines whether it rises above legal limits and can be influenced by various factors.
Step-by-step explanation:
The blood alcohol concentration (BAC) of an individual determines whether it rises above legal limits. BAC can be influenced by various factors such as age, sex, pre-existing health conditions, and the amount of alcohol consumed. In most countries, including the US, it is illegal to drive with a BAC of 0.08% or higher.