This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
A female patient after injury comes to casualty. Her ABG shows low pH. PCO2 high, bicarbonate normal.The diagnosis is - 
Select and explain. 
A. Respiratory alkalosis, B. Respiratory acidosis, C. Metabolic acidosis, D. Metabolic alkalosis
B: Respiratory acidosis
Answer: B: Respiratory acidosis 
Explanation: First step

Determine whether academia or alkalemia is present
pH is low, indicating acidosis

Second step

Inspect HCO3-/CO2 to determine the cause of alkalemia or academia.
In this case, the pCO2 is high and the bicarbonate is normal, so the acidosis can be easily attributed to increased CO2
Thus, this is a case of respiratory acidosis