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: Physiology
The gradient of alveolar arterial oxygen tension increases in All except 
Select and explain. 
A. Diffusion defect, B. Right left shunt, C. Hypoventilation, D. Ventilation perfusion abnormality
C: Hypoventilation
Answer: C: Hypoventilation 
Explanation: None