This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Electrolyte Imbalance, Subject name: Medicine
A man is found comatose in his room, having taken an unknown number of sleeping pills. An aerial blood sample yields the following values: pH 7.10, HCO3 - 12 meq/liter, PaCO2 66 mm Hg. This patient's acid - base status is most accurately described as: 
Select and explain. 
A. Uncompensated metabolic acidosis, B. Uncompensated respiratory acidosis, C. Mixed respiratory and metabolic acidosis, D. Respiratory acidosis with paial renal compensation
C: Mixed respiratory and metabolic acidosis
Answer: C: Mixed respiratory and metabolic acidosis 
Explanation: None