The Placenta Is

The placenta is:

A) formed solely from the outermost layers of the embryonic trophoblast, and serves as an exchange organ between mother and fetus.
B) formed from interlocking fetal and maternal tissues, and allows the mother's blood to flow freely into the fetal circulation and back.
C) formed solely from the endometrial layer of the uterus, and allows the mother's blood to flow freely into the fetal circulation and back.
D) formed from interlocking fetal and maternal tissues, and serves as an exchange organ between mother and fetus.
E) formed from maternal circulatory stem cells, and serves as an exchange organ between mother and fetus.