VIC Car DKT - Can you be sure of your blood alcohol concentration (BAC) when you drink alcohol?

If you only have one can of beer you can be sure your BAC will be below the legal limit.

You can be sure if you measure your BAC when you have some alcohol and then always drink the same amount.

You can never be sure of your BAC even when you drink the same amount of alcohol.

(112/170) Can you be sure of your blood alcohol concentration (BAC) when you drink alcohol?