This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Excretory System (Kidney, Bladder) Acid-Base Balance, Subject name: Physiology
Acute metabolic acidosis tends to _____ intracellular K+ concentration and _____ K+ secretion by the coical collecting tubules. 
Select and explain. 
A. Increase, increase, B. Increase, decrease, C. Decrease, increase, D. Decrease, decrease
D: Decrease, decrease
Answer: D: Decrease, decrease 
Explanation: Acute metabolic acidosis : reduces intracellular potassium concentration, which, in turn, decreases potassium secretion by the principal cells of the collecting tubules. The primary mechanism by which increased hydrogen ion concentration inhibits potassium secretion is by reducing the activity of the Na+ -K+ ATPase pump. This action then reduces intracellular potassium concentration, which, in turn, decreases the rate of passive diffusion of potassium across the luminal membrane into the tubule