The nurse is teaching a new mother about the drastic growth and developmental changes her infant will experience in the first year of life. Which statement describes a developmentalmilestone occurring in infancy?

A. Areola and papilla separate from the contour of the breast: This is a normal finding in breast development and indicates Tanner stage 4 or higher, which is typical for adolescent girls. It does not necessarily indicate a developmental delay.

B. Absence of first menstrual perioD. Menarche, the first menstrual period, typically occurs between the ages of 9 and 15 in girls. Absence of menarche by the age of 15 or within 3 years after the onset of breast development (thelarche) may indicate a developmental delay or underlying medical condition that should be evaluated by a healthcare provider.

C. Developed breast tissuE. Breast development, indicated by palpable breast tissue, is a normal part of female puberty and typically occurs before menarche. Developed breast tissue alone does not necessarily indicate a developmental delay.

D. Mature distribution and coarseness of pubic hair: Pubic hair development is also a part of female puberty and occurs before or around the time of menarche. While the distribution and coarseness of pubic hair can provide information about pubertal development, the absence of menarche is a more reliable indicator of a potential developmental delay.

A. The heart triples in size over the first year of lifE. While cardiac growth occurs during infancy, the described change is not specific to a developmental milestone.

B. Most infants triple their birth weight by 4 to 6 months of age and quadruple their birth weight by the time they are 1 year olD. This statement accurately describes a significant developmental milestone related to physical growth during infancy.

C. By 6 months of age, the infant's brain weighs half that of the adult brain; at age 12 months, the brain weighs 2.5 times what it did at birth: This statement describes brain growth rather than a

milestone related to physical growth or development.

D. The head circumference increases rapidly during the first 6 months: the average increase is about 1 in per month: While head circumference growth is important, it does not specifically relate to the described developmental milestone of weight gain during infancy.