Final answer:
The legal blood alcohol concentration (BAC) limit for someone over 21 years old is 0.08% in most US states. Option B is correct.
Step-by-step explanation:
In the United States, the legal blood alcohol concentration (BAC) limit for individuals operating a motor vehicle who are over 21 years old is 0.08%. This limit signifies the percentage of alcohol present in the bloodstream. Exceeding this limit while driving can result in legal consequences such as fines, license suspension, or even arrest for driving under the influence (DUI) or driving while intoxicated (DWI).
This limit is set based on research indicating that impairment begins at this level of alcohol in the bloodstream, affecting reaction times, coordination, and judgment, thereby increasing the risk of accidents. It's crucial for individuals to be aware of their alcohol consumption and understand how it correlates with their BAC levels to make responsible decisions, especially when operating a vehicle.
Therefore, the legal BAC limit for someone over 21 is 0.08%, as established by laws in various states within the United States and many other countries worldwide.
Correct answer: b. 0.08%