Final answer:
To ensure newborn safety in a vehicle, a nurse would instruct parents to secure the baby in a rear-facing car seat, as it offers optimal support for the infant's body during travel.
Step-by-step explanation:
The correct instruction that a nurse should include when providing discharge teaching to the parents of a newborn about car seat safety is: b) "Secure the baby in a rear-facing car seat."
This is because a rear-facing car seat provides the best support for the baby's head, neck, and spine in the event of a sudden stop or crash. Placing blankets or other loose items in the car seat is not recommended, as they can pose a suffocation risk and may interfere with the proper functioning of the car seat's restraints. The straps should be adjusted to fit snugly against the baby's body to provide proper support and safety. Additionally, car seats should always be placed in the back seat, away from active airbags, to protect the child.