What best describes the function of the placenta during pregnancy?

The placenta serves a critical role during pregnancy primarily as the site for the exchange of oxygen and nutrients between the mother and the fetus. It facilitates this exchange through its specialized structure, which allows for efficient transfer of essential substances while also enabling the removal of waste products from the fetal circulation.

This process is vital for fetal development, as the fetus relies entirely on the mother for these resources throughout pregnancy. The placenta's vascular network and its ability to selectively permeate certain substances ensure that the fetus receives adequate nutrition and oxygen, which are crucial for growth and development.

While the placenta does perform additional functions, such as producing hormones that support pregnancy and offering some degree of protection against certain infections, its primary and most crucial role remains the exchange of oxygen and nutrients. Other options, although they contain elements of truth regarding the placenta's functions, do not encompass the primary and essential role played by the placenta in a straightforward manner.