Which restraint is applicable for a child who is under 1 year of age?

The correct option highlights the use of a rear-facing child restraint system for a child under one year of age, which is crucial for their safety. Infants and toddlers are particularly vulnerable in the event of a collision, and rear-facing seats are designed to provide optimal support for their developing bodies. These seats help absorb the force of a crash while protecting the child's head, neck, and spine, which are still quite fragile.

Using a rear-facing child restraint is consistent with safety recommendations from pediatricians and traffic safety organizations, emphasizing that children should remain in this position until they reach the maximum height or weight limit set by the car seat manufacturer. This practice is proven to significantly reduce the risk of injury during an accident, showcasing why this type of restraint is the safest option for very young passengers.