Final answer:
The baby is doing great because they have regained birth weight, exhibit typical nursing frequencies, and have an adequate number of wet and soiled diapers, indicating proper nutrition and hydration.
Step-by-step explanation:
The scenario presented indicates that the breastfeeding infant nurses 8-9 times a day, has regained birth weight, has 6-8 wet diapers, and typically has one bowel movement per day. Considering these factors, the most appropriate response from the nurse would be to reassure the mother that her baby is doing great. Since the infant has regained their birth weight and is producing the expected number of wet and soiled diapers, this suggests that nutritional intake and hydration are adequate. Additionally, frequency in bowel movements can vary for breastfed babies, and one bowel movement per day can be normal. Thus, there is no need to worry about the number of daily bowel movements as long as they are soft and the baby is comfortable.