Answer:
is b casue the other are like what they do but bear to sleep takes a long time to evole into doing that
Explanation:
B. Increased fitness of large-beaked birds, leading to natural selection
Umbilical vein transports blood rich in oxygen and nutrients from the placenta to the fetus. The unpaired umbilical vein is a vein present during fetal development and it transports the nutrient- and oxygen-rich blood from the placental villi via the umbilical cord to the embryo. The umbilical vein is connected to the two intraembryonic umbilical veins.