Due to increasing air-borne allergens and pollutants, many people in urban areas are suffering from respiratory disorder causing wheezing due to :

Question

( A ) reduction in the secretion of surfactants by pneumocytes.
( B ) benign growth on mucous lining of nasal cavity.
( C ) proliferation of fibrous tissues and damage of the alveolar walls.
( D ) inflammation of bronchi and bronchioles.