How can injuries and deaths resulting from traffic crashes be greatly reduced?

Answer: C — By wearing safety belts

Wearing safety belts can greatly reduce injuries and deaths resulting from traffic crashes because they are designed to restrain the body during a collision and prevent ejection from the vehicle. Using safety helmets may only provide protection for the head and not the rest of the body, and driving faster can actually increase the risk of a crash. Using brighter headlights may improve visibility, but it is not a reliable method for reducing injuries and deaths in traffic crashes. Wearing safety belts is the most effective and widely recommended solution for preventing severe injuries and fatalities in car accidents.