A pregnant female comes to her physician with questions about the effect that ingested substances may have on her unborn child. The physician explains that large molecules do not pass between the mother and fetus because of the placental barrier. The physician adds that fetal blood is in the fetal blood vessels of the villi of the placenta and the mother's blood is in the maternal blood vessels, and that these blood vessels do not connect. The placental villi are formed from which of the following cells?

1. A)Epiblast
2. B)SyncytiotrophoblastGABARITO
3. C)Embryoblast
4. D)Endometrium
5. E)Cytotrophoblast