The correct option is D Spasm in bronchial muscle
Asthma
Asthma is a chronic condition of lungs characterised by swelling of bronchi and spasms in muscles of bronchioles. This leads to constriction of the airways and obstructs the flow of air. Asthma patients might feel difficulty in breathing and chest tightness along with persistent coughs.
Final answer
(A) Spasm in bronchial muscle