Which of the following describes the role of the placenta during pregnancy?

The role of the placenta during pregnancy is crucial, as it is responsible for the transfer of nutrients and immunities from the mother to the fetus. The placenta acts as a highly efficient interface, allowing essential substances like oxygen, glucose, and antibodies to pass from the mother's bloodstream to the fetus. This transfer is vital for the development and survival of the fetus, enabling it to receive the necessary resources for growth and protection against infections.

Additionally, the placenta plays a role in waste removal, allowing byproducts produced by the fetus to be transported back to the mother for elimination. While the other functions mentioned have their significance, they do not accurately capture the primary purpose of the placenta. It does not function as a filter for all toxins, nor does it serve as a fluid barrier or a respiratory organ; these aspects are either oversimplifications or misattributions of the placenta's function. Recognizing the placenta's role in nutrient and immunity transfer emphasizes its importance in the overall health of both the mother and the developing baby.