In North Dakota, the legal BAC limit for drivers over 21 is:

The legal blood alcohol concentration (BAC) limit for drivers over the age of 21 in North Dakota is set at 0.08%. This means that if a driver has a BAC of 0.08% or higher, they are considered legally impaired and can face penalties if caught driving under the influence.

This limit is based on both national and state laws that aim to enhance road safety by reducing accidents caused by impaired driving. When BAC levels reach this threshold, it significantly impairs a person's coordination, judgment, and reaction time, increasing the likelihood of accidents on the road.

The other options represent levels that are either too low or too high compared to the established legal limit. For example, a BAC of 0.05% may be permissible for certain professional drivers or might relate to different legal definitions for other activities, but it does not apply to standard driving conditions for those over 21. Likewise, higher BAC levels like 0.10% and 0.15% are well above the legal threshold and would categorize a driver as significantly impaired, leading to more severe penalties. Understanding the legal BAC limit is crucial for ensuring safe driving practices and compliance with state laws.