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
ABG analysis of a patient on ventilator, shows decreased pCO2, normal pO2, pH 7.5, diagnosis is - 
Select and explain. 
A. Resp. acidosis, B. Metabolic alkalosis, C. Resp. alkalosis, D. Metabolic acidosis
C: Resp. alkalosis
Answer: C: Resp. alkalosis 
Explanation: First step

Determine whether academia or alkalemia is present by observing the pH.
pH is increased, indicating alkalosis

Second step

Inspect HCO3- /CO2 to determine the cause of academia or alkalemia
pCO2 is decreased indicating respiratory alkalosis.