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: Radiology
Dirty chest appearance on CXR is seen in? 
Select and explain. 
A. Chronic bronchitis, B. TB, C. Bronchiectasis, D. Cystic fibrosis
A: Chronic bronchitis
Answer: A: Chronic bronchitis 
Explanation: Ans ADirty chest appearance-because of recurrent infection with scarring, the bronchovascular structures have irregular contours. This is the only sign of bronchitis in chest X-ray.