What must drivers ensure for their passengers regarding safety?

Answer: B — They must wear installed seatbelts

Drivers are responsible for ensuring the safety of their passengers, and one fundamental aspect of this responsibility is making sure that all passengers wear installed seatbelts. Wearing seatbelts significantly reduces the risk of injury or death in the event of an accident by keeping passengers securely in their seats and preventing them from being thrown forward or ejected from the vehicle. Seatbelts are designed to absorb the force of a collision, minimizing the impact on the occupants of the vehicle. This is a critical safety measure, and drivers must ensure that all passengers are buckled up before the vehicle moves. The other options either encourage unsafe behavior, such as standing while the vehicle is moving or using handheld devices, or do not directly contribute to passenger safety in the same way that seatbelt use does.