How should head restraints be adjusted if they are adjustable?

Answer: B — Against the back of the head

The head restraints in a vehicle are designed to reduce the risk of whiplash and other neck injuries in the event of a rear-end collision. For them to be effective, they should be positioned correctly. When properly adjusted, the head restraint should be located as close to the back of the head as possible. This positioning minimizes the amount of backward movement the head can experience during a collision, thereby providing better support and protection. Positioning the head restraints against the back of the head ensures that they can effectively limit the head's backward movement and absorb the impact in a crash scenario. Other positions, like having the restraint at the lowest point or below the ears, can increase the distance between the head and the restraint, making it less effective and potentially allowing for greater movement of the head during an accident. Removing the head restraint altogether eliminates its intended safety function, significantly increasing the risk of injury.