The correct answer is that mammals use a closed, double loop , four chambered heart as a circulatory system of the body.
The circulatory system of mammals is closed system that consists of four chambers, two articles and two ventricles. The deoxygenated blood comes into the heart from one loop and the oxygenated blood from other loop from the heart is circulated to the whole body. This is called as double circulation.
I don’t think we would have the same countries. i feel like everything would be connected, like maybe a few really big countries instead of hundreds of different countries. i feel we would look different that how we already look because there would be more of different type of people around each other, resulting in mixed race reproducing.
D)
Because a scientific theory is something that has been proven over the trials of many tests
Hope that helps :)
One: The cell is able to move material in and out of the cell
Two: It helps the cell maintain necessary conditions for life
