The placental blood vessels
A) manufacture hormones that slow the growth of the embryo, preventing it from outgrowing the uterus.
B) allow for the exchange of wastes and nutrients but keep the maternal and fetal circulations separate.
C) draw oxygen from the fetal blood and pass it to the mother.
D) mix maternal blood and fetal blood.
E) prevent all microbes and toxins from crossing from mother to child.
B
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