In a patient experiencing metabolic acidosis, which of the following mechanisms is primarily responsible for the kidney's compensatory response to excrete excess acid?

✓ Correct Answer: Option B

In metabolic acidosis, the kidneys compensate by increasing H+ secretion, primarily via the H+-ATPase in Type A intercalated cells of the collecting ducts, and by increasing ammonium (NH4+) excretion, which involves ammonia synthesis.