It is illegal for a person 21 years of age or older to drive with a minimum blood alcohol concentration (BAC) of:
- 0.05 percent.
- 0.08 percent. ✓
- 0.02 percent.
- 0.1 percent.
Answer: B. 0.08 percent.
For a driver 21 or older, it is illegal to drive with a blood alcohol concentration of 0.08 percent or more.
Why this is the answer
The handbook says a person is legally intoxicated at a blood alcohol concentration of 0.08 or more, and it repeats that anyone with 0.08 or more is considered intoxicated. It also ties the adult license suspension rule to a test result showing 0.08 or more. Because the question asks for the minimum BAC that makes driving illegal for an adult, the threshold is 0.08 percent. The lower figures are below the stated adult limit, and 0.1 percent is above it rather than the minimum.
Why the other answers are wrong
- A. 0.05 percent. — A BAC of 0.05 percent is below the 0.08 percent level the handbook uses for adult legal intoxication.
- C. 0.02 percent. — A BAC of 0.02 percent is lower than the handbook's 0.08 percent adult intoxication threshold.
- D. 0.1 percent. — A BAC of 0.1 percent is higher than the legal threshold; the question asks for the minimum, which is 0.08 percent, not a higher figure.
Remember it
Remember the adult line as 0.08: at that level or above, Texas treats the driver as intoxicated.