Final answer:
In New Jersey, if you are under 21, being under the influence means having a blood alcohol level above the legal limit.
Step-by-step explanation:
In the state of New Jersey, if you are under the age of 21, you may be considered under the influence if your blood alcohol level is above the legal limit. The legal limit for blood alcohol concentration (BAC) in most US states, including New Jersey, is 0.08% by volume. It is important to note that even a BAC as low as 0.02% can impair a person's ability to drive and make sound judgments.