Final answer:
The nurse would use normal saline to demonstrate the cleaning of the lip repair site to the parents as it is gentle on the tissues and promotes healing without causing skin irritation or interfering with the healing process.
Step-by-step explanation:
The nurse would use normal saline to demonstrate the cleaning of the lip repair site to the parents. Normal saline is a mild and non-irritating solution that is commonly used for wound cleaning. It is gentle on the tissues and helps to remove debris and promote healing. Unlike other solutions mentioned, such as hydrogen peroxide or betadine, normal saline does not have antiseptic properties that may cause skin irritation or interfere with the healing process.