What Factor Would Limit the Ability of the H₂CO₃/HCO₃^- Buffer $\circ$

What factor would limit the ability of the H₂CO₃/HCO₃^- buffer system to perform efficiently?

A) temperature rise of more than 3 ^$\circ$ C
B) inadequate amount of 2,3-DPG in the blood
C) increased production of nonvolatile acids
D) lungs failing to excrete adequate levels of CO₂