What is the MAIN reason the author includes the section "Pathway Of Blood Through The Heart"? A
to emphasize to readers the crucial role oxygen plays in supporting the pumping function of the heart
B
to give readers a better idea of the complexity involved in keeping the human body alive
C
to illustrate for readers the overall reason the heart is divided into four separate chambers and functions as two pumps instead of one
D
to give readers a fuller understanding of how all the parts of the heart work simultaneously to function as a whole