How many seconds of space is needed for a 60 ft vehicle traveling under 40 mph?

Answer: B — 6 seconds

When driving a commercial vehicle, it is crucial to maintain a safe following distance to ensure enough time to react and stop if necessary. The general rule of thumb is to maintain at least one second of following distance for every 10 feet of vehicle length. In this case, with a 60 ft vehicle, you would need at least 6 seconds of following distance when traveling under 40 mph. This calculation ensures that you have enough time to stop safely in various driving conditions, helping to prevent accidents and maintain road safety. Therefore, the correct answer is B.