Final answer:
The parent's understanding is reflected by their intention to introduce a new solid food every 5 days to their 4-month-old infant, which is the right approach to ensure proper adjustment and allergy monitoring. Breast milk remains the primary nutritional source during early infancy, with solid foods being supplementary.
Step-by-step explanation:
The correct statement by the parent that indicates an understanding of the teaching about the introduction of solid foods to a 4-month-old infant is "I will introduce a new solid food every 5 days." This practice allows the infant's digestive system to adjust to the new food and makes it easier to identify any potential food allergies or intolerances. It's important to note that for the first several months of life, an infant's primary source of nutrition should still be breast milk or formula, with solid foods gradually introduced as a supplement.
During the first days of lactation, the composition of breast milk changes significantly; it starts as colostrum, which is rich in antibodies and nutrients critical for the newborn's immune system. In the course of a single feeding, the fat content of breast milk usually increases from the beginning to the end, providing essential energy and aiding infant growth. This is why a healthy baby requires significant daily milk intake for optimal development.