Who must wear a seatbelt in Washington State?

In Washington State, the law requires that all passengers in a vehicle must wear a seatbelt, regardless of their age or seating position. This regulation is in place to enhance safety for everyone in the vehicle, as seatbelts significantly reduce the risk of injury or death in the event of a crash.

While other options suggest limited requirements based on specific roles or ages, the law's emphasis on universal seatbelt use reflects the understanding that all occupants are at risk in an accident, and safety measures should apply to everyone equally. This comprehensive approach helps to ensure that all passengers are protected, which is why the correct answer is that all passengers in a vehicle must wear a seatbelt.