Answer:
A. By testing breath, blood, or urine.
Step-by-step explanation:
BAC (blood alcohol concentration) levels are determined by measuring the amount of alcohol in a person's bloodstream. This can be done by testing a person's breath, blood, or urine. Breathalyzers are typically used to measure BAC by measuring the amount of alcohol in a person's breath. At the same time, blood and urine tests can also be used to measure BAC by measuring the amount of alcohol present in the blood or urine sample. Field sobriety tests are not used to measure BAC but to check the person's sobriety. It's the responsibility of a trained Law Enforcement Officer to carry out these tests and they usually follow the standard procedure.