I think the correct answer would be A. The yolk sac becomes the placenta. It is membranous sac that is attached to the embryo. It provides all the nutrition and the blood cells needed by the embryo. It is also called the umbilical vesicle.
Answer:
A walrus stays warm in the cold ocean or penguins can stay warm in cold arctic waters.
These microbial infections that are acquired by hospital patients as they are being used as the compromised host are the nosocomial infections. These type of infections are primarily caused by bacterial pathogens entering the patient's body and mainly causes urinary tract infection, pneumonia, and other illnesses.
