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 statements about emphysema -a) Breathlessness is always thereb) Diffusion rate for carbon monoxide is reducedc) Restrictive pattern of lung diseased) Long-term bronchodilator therapy is not effective 
Select and explain. 
A. acd, B. abd, C. abc, D. ab
B: abd
Answer: B: abd 
Explanation: None