What is the maximum allowable blood alcohol concentration (BAC) for a commercial driver?

Answer: B — 0.04%

The maximum allowable blood alcohol concentration (BAC) for a commercial driver is 0.04%. This limit is significantly lower than the BAC limits for non-commercial drivers, reflecting the responsibility that commercial drivers have while operating large vehicles or transporting passengers and cargo. A lower BAC limit is enforced for commercial drivers because they must maintain a heightened level of focus and control, as the size and weight of commercial vehicles can make them more difficult to maneuver compared to standard vehicles. Operating under the influence of alcohol at any level presents a danger, so the regulations aim to enhance road safety. The other BAC levels referenced in the options are either above the legal limit for commercial drivers or pertain to different categories of drivers, emphasizing the stricter standards that apply to those driving commercial vehicles.