As we inhale air, oxygen enters the respiratory system and the circulatory system to transport it to the other parts of the body and to all cells. As the oxygen is already transported, the blood becomes deoxygenated and carries a CO2 which returns to the lungs and then we exhale the carbon dioxide.
Some offsprings look like their parents because we all have different genes. Different combinations of genes for one of these traits create a bunch of different physical attributes. Even though we get all our DNA from our parents, each of us has a unique combination of genes.
1.)<span>a. antibodies
2.)</span><span>b. its mechanism is well understood</span>
I believe the answer would be Letter
B. Psychology
