Question

the allantois
a is the first site of blood cell formation
b forms the fetal half of the placenta
c becomes the umbilical cord vessels
d cushions and protects the embryo with fluid

Explanation:

• The allantois is an extra - embryonic membrane.
• It contributes to the formation of the umbilical cord vessels.
• The yolk sac is the first site of blood cell formation (so A is wrong).
• The chorion forms the fetal half of the placenta (so B is wrong).
• The amnion cushions and protects the embryo with fluid (so D is wrong).

Answer:

C. becomes the umbilical cord vessels