Answer:
The placenta is a unique vascular organ that receives blood supplies from both the maternal and the fetal systems and thus has two separate circulatory systems for blood: (1) the maternal-placental (uteroplacental) blood circulation, and (2) the fetal-placental (fetoplacental) blood circulation. The uteroplacental circulation starts with the maternal blood flow into the intervillous space through decidual spiral arteries. Exchange of oxygen and nutrients take place as the maternal blood flows around terminal villi in the intervillous space. The in-flowing maternal arterial blood pushes deoxygenated blood into the endometrial and then uterine veins back to the maternal circulation. The fetal-placental circulation allows the umbilical arteries
Explanation:
The answer is probably B because white blood cells are part of the immune system, so help to fight diseases. The circulatory system helps to move the white blood cell around the body. Also, pathogens are disease causing organisms, and as you can see, they all relate very well. Hope i helped, have a nice day.
The S wave penetrate the interior of he earth
shake the ground perpendicular to the direction in which they are propageting.
It does not travel through liquids.
1.7 times slower than P waves
1.rivers and streams
2.seepage from the ground
XYLEM AND PHLOEM.................
