The diagram illustrates some of the events occurring between the plasma and the red blood cells in the circulatory system. What do the numbers 1, 2, 3 and 4 stand for?
- A1: $\text{Cl}^-$, 2: $\text{HCO}_3^-$, 3: $\text{H}^+$, 4: $\text{CO}_2$
- B1: $\text{CO}_2$, 2: $\text{HCO}_3^-$, 3: $\text{H}^+$, 4: $\text{Cl}^-$
- C1: $\text{HCO}_3^-$, 2: $\text{Cl}^-$, 3: $\text{CO}_2$, 4: $\text{H}^+$
- D1: $\text{CO}_2$, 2: $\text{H}^+$, 3: $\text{HCO}_3^-$, 4: $\text{Cl}^-$