Practice question What is the purpose of the hours-of-service (HOS) regulations? To prevent you from driving when you are tiredTo make sure you are alert and able to drive safelyTo comply with the lawAll of the above Answer: D — All of the above The correct answer is shown above. Try the full quiz for additional practice. Practice more: CDL Passenger Endorsement Practice Questions - CDL Passenger Endorsement (P) Exam →