This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Anatomy
All are decreased in infiltrative lung disease except 
Select and explain. 
A. Vital capacity, B. Alveolar aerial difference in PaO2, C. Total lung capacity, D. Lung compliance
B: Alveolar aerial difference in PaO2
Answer: B: Alveolar aerial difference in PaO2 
Explanation: In infiltrative lung disease the alveolar capillary bed is damaged and there is a decrease in diffusion capacity.this results in an increase in alveolar aerial differences in PaO2 Ref Harrison 19th edition pg 1710