This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory Failure, Subject name: Medicine
pH = 7.30, pCO2 = 38, HCO3 = 18 signifies: 
Select and explain. 
A. Metabolic acidosis with compensatory respiratory alkalosis, B. Respiratory acidosis with compensatory metabolic alkalosis, C. Respiratory alkalosis with compensatory metabolic acidosis, D. Metabolic acidosis with respiratory acidosis
D: Metabolic acidosis with respiratory acidosis
Answer: D: Metabolic acidosis with respiratory acidosis 
Explanation: * Since pH is less, and HCO3 is less it implies metabolic acidosis. * Now for compensation pCO2= HCO3+15 = 18 + 15 = 33. * The value predicted is not matching with given pCO2 of 38 mm Hg. * It implies compensation is not there and it is a Mixed disorder * Conclusion metabolic acidosis with respiratory acidosis