Q: A fully developed placenta is made up of a large mass of what?


Read this paragraph and choose the correct option from the provided answers:

A fully developed placenta, like the one in Figure below , is made up of a large mass of blood vessels from both 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.

 Choices:

- brain tissues

- plant cells

- estrogen hormones

- blood vessels


A:
blood vessels