A nurse is reinforcing teaching with new parents about car seat safety. Which of the following instructions should the nurse include?

A. "Position the car seat at a 90° angle." Positioning the car seat at a 90° angle is not recommended. The car seat should be reclined at an angle of 30 to 45 degrees to ensure that the infant's head does not flop forward, which can obstruct the airway. B. "Keep the airbag on if the car seat is in the front seat." Keeping the airbag on when a car seat is in the front seat is unsafe. It is recommended to place the car seat in the back seat, as the force of an airbag deploying can be harmful to a child in a car seat. C. "Put a small cushion under the newborn's head for support." Placing a cushion under the newborn's head is not recommended, as it can interfere with the proper positioning of the car seat and compromise the safety of the infant. The car seat is designed to provide support without additional cushions. D. "Place the shoulder harnesses at the level of the infant's shoulders." Placing the shoulder harnesses at the level of the infant's shoulders is the correct practice. The harnesses should be positioned snugly at or just above the shoulders for optimal safety, ensuring that the infant is securely restrained in the car seat.