The placenta develops within the first couple of weeks of pregnancy. The placenta is the lifeline of the fetal body and soon after the placenta is developed and in place, it begins starting to absorb nutrients for the developing fetus. This all occurs in the first trimester.
The answer is evolutionary!
I hope I was able to help. :)
Answer:
B Heart and lungs
Explanation:
The thoracic cavity is another term for the chest cavity. It is enclosed by the ribs, spine, and breast bone, and is separated from the abdomen by the diaphragm.
It contains the heart, lungs, and the esophagus, and the blood vessels that supply them.
Most allergic reactions occur with rashes and trouble breathing.