Answer:
B. as the bicarbonate ion in the plasma after first entering the red blood cells
Explanation:
Carbon dioxide is exchanged from the deoxygenated tissues into the red blood cells. Inside the red blood cells, an enzyme known as carbonic anhydrase which catalyses reaction of CO₂ with H₂O and form H₂CO₃ (carbonic acid) which further dissociates into bicarbonate ion, HCO₃⁻ and H⁺.
CO₂ + H₂O ⇄ HCO₃⁻ + H⁺
This bicarbonate ion thus formed is exchanged to the plasma in the exchange of the chloride ions, Cl⁻. Thus, Carbon dioxide is transported in the blood in this form.
Hence, Option B is correct.
