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
True about interstitial fibrosis -a) FVC↓b) FEV1/FVC normal or increasedc) FRC normald) FEV1/FVC ↓ 
Select and explain. 
A. ac, B. a, C. ad, D. ab
D: ab
Answer: D: ab 
Explanation: None