Answer the following question given this paragraph: The placenta is a temporary organ that begins to form from the trophoblast layer of cells shortly after implantation. (For an animation showing how the placenta forms, go to link below. ) The placenta continues to develop and grow to meet the needs of the growing fetus. A fully developed placenta, like the one in Figure above , is made up of a large mass of blood vessels from both the mother and fetus. The maternal and fetal vessels are close together but separated by tiny spaces. This allows the mother's and fetus's blood to exchange substances across their capillary walls without the blood actually mixing. Q: What is the name of the temporary organ that begins to form from the trophoblast layer of cells shortly after implantation? A:

Choose your answer from:
A). uterus
B). embryo
C). appendix
D). placenta
The answer is:
D).