When is it mandatory for truck drivers to use seatbelts?

Answer: C — At all times while the vehicle is in motion

The correct answer is that it is mandatory for truck drivers to use seatbelts at all times while the vehicle is in motion. This regulation is in place to enhance safety for both the driver and any passengers in the vehicle. Wearing a seatbelt significantly reduces the risk of injury or fatality in the event of an accident, making it a critical safety measure. Laws requiring seatbelt use are typically enforced regardless of the type of road, time of day, or whether passengers are present, highlighting the universal importance of this safety practice. Therefore, the choice emphasizing the need to wear a seatbelt at all times while driving aligns with safety regulations designed to protect drivers and their passengers fully.