Final answer:
Drivers on a 7-day cycle are limited to 70 hours of on-duty time over 7 consecutive days as per Hours of Service regulations.
Step-by-step explanation:
Drivers on a 7-day cycle must not drive after 70 hours of on-duty time in 7 consecutive days. So the correct answer to the student's question is option c) 70 hours. This rule is part of the Hours of Service regulations that govern how long drivers can operate commercial motor vehicles in order to ensure they remain well-rested and safe on the roads. Drivers on a 7-day cycle are limited to 70 hours of on-duty time over 7 consecutive days as per Hours of Service regulations.