Exchange of bicarbonates and chloride ions between RBC and plasma is called as

The correct option is A Chloride shift
In plasma, carbon dioxide slowly combines with water to form carbonic acid. This reaction proceeds much more rapidly inside RBCs as a result of the action of the enzyme carbonic anhydrase. Carbonic acid dissociates, forming hydrogen ions and bicarbonate ions. Most hydrogen ions released from carbonic acid, combine with hemoglobin, which is a very effective buffer. Many of the bicarbonate ions diffuse into the plasma. The action of carbonic anhydrase in the RBCs maintains a diffusion gradient for carbon dioxide to move into and then out of RBCs. As the negatively charged bicarbonate ions move out of RBCs, chloride ions from the plasma diffuse into the RBCs to replace them, a process known as the chloride shift. In the alveolar capillaries, $C{O}_2$ diffuses out of the plasma and into the alveoli. As the $C{O}_2$ concentration decreases, the above reaction sequence reverses.