Which of These Statements Applies to the Following Reaction: Prot-NH₂

Which of these statements applies to the following reaction: Prot-NH₂ + CO₂ Prot-NHCOO^- + H⁺?

A) Approximately 20% of the total blood carbon dioxide is carried in this form.
B) It is second in importance to only the bicarbonate buffer system.
C) It represents the formation of blood carbamino compounds.
D) The resulting H⁺ ions are buffered by reduced HCO_3.