A carrier cannot allow a driver to drive if they have already accumulated how many hours of 'on-duty time'?

The correct answer is based on regulations concerning hours of service for commercial drivers. Under the National Safety Code, a driver is not permitted to drive after accumulating 14 hours of on-duty time in a day, which includes all time spent working or being available for work. This limit ensures that drivers have adequate rest and are not fatigued, thereby enhancing safety on the roads.

Choosing a lower number, such as 10 or 12 hours, does not reflect the regulations that specifically set the 14-hour limit prior to a required rest period. Similarly, while a 16-hour threshold might seem like a reasonable option, it exceeds the maximum allowable on-duty time and could put both the driver and the public at risk due to potential fatigue. Understanding these limits is essential for compliance and promotes safety within the transportation industry.