Which of the following contributes to metabolic acidosis in acute kidney injury?

A. Decrease in secretion of hydrogen ions is correct because in acute kidney injury (AKI), the kidneys lose their ability to excrete hydrogen ions effectively. This leads to accumulation of acids in the blood, resulting in metabolic acidosis. Additionally, impaired kidney function reduces bicarbonate reabsorption, further worsening acidosis. B. Increase in production of bicarbonate from the kidneys is incorrect because bicarbonate production is reduced in AKI, not increased. Adequate bicarbonate is necessary to buffer acids, and its reduction contributes to metabolic acidosis. C. Rapid breathing is incorrect because rapid breathing (Kussmaul respirations) is a compensatory response to metabolic acidosis, not a cause. It occurs as the body attempts to blow off CO₂ to reduce acid levels. D. Increased blood pressure is incorrect because while hypertension may be associated with kidney injury, it does not directly contribute to metabolic acidosis. The acid-base imbalance is primarily due to renal failure to excrete hydrogen ions and conserve bicarbonate.