The transport of CO2 by blood is primarily dependent on
Capacity of blood proteins
Availability of Carbonic anhydrase
CO2 solubility in blood
Presence of other blood proteins
Carbon dioxide is transported in blood in the form of bicarbonates with the help of enzyme Carbonic anhydrase. Bicarbonates are the main form in which CO2 is delivered. The CO2 from the tissues reaches the RBCs where it reacts with water to create carbonic acid (H2CO3). Then carbonic acid separates into the ions H + and bicarbonate (H2CO3).
Option 2 is the correct aswer.