In Response to Metabolic Acidosis,the Kidneys Increase the Excretion of Net

In response to metabolic acidosis,the kidneys increase the excretion of net acid.Which of the following is the most important component of this compensatory response?

A) Increased filtered load of HCO₃⁻
B) Enhanced reabsorption of HCO₃⁻ by the proximal tubule
C) Increased synthesis and excretion of NH₄⁺
D) Reduced H⁺ secretion by the distal tubule and collecting duct
E) Reduced secretion of HCO₃⁻ by the collecting duct