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
Type - 2 Respiratory Failure is seen in 
Select and explain. 
A. Pneumonia, B. Atelectasis, C. COPD, D. Pulmonary Embolism
C: COPD
Answer: C: COPD 
Explanation: Type - 2 Respiratory Failure is hypoxia + hypercapnia.
p(A - a) O2 is normal or decreased seen in conditions of decreased respiratory drive(Brainstern injury),airway disease(EOPD,ASTHMA),paralusis of Diaphragm,Kyphoscoliosis,Myasthenic erisis.