A 65 year old man presents with progressively worsening breathlessness and productive cough

A 65 year old man presents with progressively worsening breathlessness and productive cough.
He has a history of treated tuberculosis and rheumatoid arthritis, he smoked 20 cigarettes/day since 35
years. When he was given a trial of salbutamol nebuliser, FEV1/FEV changed from 1.7/2.0 to 1.8/2.1
(predicted 3.0/3.5). What is the most probable diagnosis?

A. Chronic bronchitis
B. Bronchiectasis
C. Bronchial carcinoma
D. Asthma
E. Pulmonary fibrosis