Final answer:
The correct answer is a, as lanugo appears at 12 weeks of gestation. Eyelashes and eyebrows grow later during the 21-30 week period, not at 28 weeks, and initial scalp hair growth begins around weeks 13-16.
Step-by-step explanation:
The correct development related to the integumentary system is: a.Very fine hairs called lanugo appear at 12 weeks of gestation. According to fetal development information, fine, colorless hair known as lanugo starts to grow on the fetus's face during this period and will eventually cover most of the body. It is then shed close to birth. Eyelashes and eyebrows, in contrast, begin to grow during the 21-30 week gestation period, and the eyelids are no longer fused and can open and close. Fingernails and toenails start to develop by the end of week 12, as the fingers and toes finish forming. By around weeks 13-16, the scalp starts to grow hair, indicating initial hair development much earlier than 32 weeks.