Passage: "A blood alcohol concentration, or BAC, measures the amount of alcohol in a person's bloodstream. In South Carolina and across the United States, a driver age 21 or older is considered legally impaired at a BAC of 0.08 percent or higher. The limit is stricter for commercial and underage drivers." According to the passage, at what BAC is a driver age 21 or older considered legally impaired?

1. 0.05 percent
2. 0.08 percent
3. 0.10 percent
4. 0.15 percent