This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ABG Analysis Simplified, Subject name: Medicine
Lab values: pH 7.56, paCO2- 20, HCO3- 20 .Interpret? 
Select and explain. 
A. Respiratory alkalosis, uncompensated, B. Respiratory alkalosis, compensated, C. Respiratory alkalosis, paially compensated, D. Metabolic alkalosis, paially compensated
C: Respiratory alkalosis, paially compensated
Answer: C: Respiratory alkalosis, paially compensated 
Explanation: pH - 7.56 (Alkaline) PaCO2 - 20 (low) HCO3 - 20 (low) * So this is Respiratory alkalosis * PaCO2 | by 20 mm Hg * So HCO3 to be | by 4x2=8 * HCO3 to be b/w (14 -18) * HCO3 in question 20 & pH-alkaline So respiratory alkalosis but paially compensated