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
Use the following laboratory values find the best option to describe acid-base disorder: Plasma pH = 7.12 Plasma Pco2 = 60 mm Hg Plasma = 19 mEq/L 
Select and explain. 
A. Respiratory acidosis with renal compensation, B. Metabolic alkalosis with respiratory compensation, C. Combined metabolic and respiratory acidosis, D. Combined metabolic and respiratory alkalosis
C: Combined metabolic and respiratory acidosis
Answer: C: Combined metabolic and respiratory acidosis 
Explanation: pH < 7.4, thus acidosis Pco2 > 40 mm Hg, thus respiratory acidosis HCO3- < 24 mEq/L, thus metabolic acidosis