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
About respiratory failure, the following is false: 
Select and explain. 
A. Type III failure involves post-operative atelectasis, B. Type II failure doesn’t have fall in paO2 (hypoxia), C. Type I failure involves hypoxia (paO2), D. Pneumonia usually presents with type I respiratory failure
B: Type II failure doesn’t have fall in paO2 (hypoxia)
Answer: B: Type II failure doesn’t have fall in paO2 (hypoxia) 
Explanation: Type I or Hypoxemic respiratory failure is characterized by PaO2 <60 mm Hg with a normal or low arterial carbon dioxide tension. 

Causes:- Pneumonia, ARDS, pulmonary embolism, pulmonary edema 

Type II or Hypercapnic respiratory failure is characterized by a PaCO2 >50 mm Hg. May be associated with hypoxemia. 

Causes:- Drug overdose, neuromuscular disease, chest wall abnormalities, and severe airway disorders (eg, asthma and COPD) 

Type III failure involves post-operative atelectasis.
Type IV failure is due to decreased blood flow to respiratory muscles.