How Does CO₂ Affect Hemoglobin-Oxygen Binding

How does CO₂ affect hemoglobin-oxygen binding?

A) CO₂ binds directly to the oxygen binding site, displacing oxygen and thus promoting the deoxy state
B) CO₂ displaces BPG, thus promoting the oxy state
C) CO₂ is converted to bicarbonate and H⁺ which promotes the oxy state
D) CO₂ is converted to bicarbonate and H⁺ which promotes the deoxy state
E) none of the above