Why does the transfer of carbon and oxygen take place

The transfer of the  carbon-dioxide and oxygen occurs during the process of the respiration. The oxygen from the air we breathe in our lungs is diffused into the blood present in the capillaries surrounding the alveloi of the lungs. The carbon-dioxide is diffused into the lungs, which is then breathed out. This transfer of the gases is necessary as the oxygen is required by the body to break down the fatty acids and other components in order to release energy for different processes of the body. The carbon-dioxide released after the generation of the energy is eliminated from the body by this exchange.

currents is the correct answer.