| A. | Diffusion of \(O_2\) and \(CO_2\) between blood and tissues |
| B. | Diffusion of \(O_2\) and \(CO_2\) across alveolar membrane |
| C. | Pulmonary ventilation by which atmospheric air is drawn in and \(CO_2\) rich alveolar air is released out |
| D. | Cellular respiration |
| E. | Transport of gases by the blood |