Final answer:
A car seat should be rear-facing until a child reaches 2 years of age or 20 lb, which is the guideline for minimizing injury risk in an accident.
Step-by-step explanation:
A car seat should be rear facing until the child is 2 years of age or 20 lb. According to the American Academy of Pediatrics, it is recommended to keep children in a rear-facing car seat for as long as possible, at least until they reach the maximum height or weight limit allowed by the car seat manufacturer. This is because rear-facing seats provide better support for the head, neck, and spine of infants and toddlers in the event of a crash, thereby reducing the risk of injury. Once they outgrow the rear-facing seat, they should transition to a forward-facing car seat with a harness.