Final answer:
The correct statement about placenta structure and function is that it secretes both estrogen and progesterone, hormones critical to maintaining pregnancy and fetal development, along with facilitating nutrient and waste exchange between mother and fetus.
Step-by-step explanation:
The structure and function of the placenta are integral to pregnancy and fetal development. The correct statement regarding the placenta's role is that it secretes both estrogen and progesterone. These hormones are vital for maintaining the pregnancy, with progesterone suppressing uterine contractions to prevent preterm birth and estrogen promoting tissue growth in the mother and fetus. Additionally, the placenta mediates the transmission of hormones, like human chorionic gonadotropin (hCG), which supports the corpus luteum and stimulates the fetal gonads to secrete testosterone. As an essential organ, the placenta is also involved in the exchange of gases, nutrients, and waste between the mother and fetus, although it does not form an impermeable barrier to all microorganisms.