Answer: Option D
Explanation:
Asthma is an obstructive pulmonary disorder in which there the bronchial tubes are extra sensitive. The passage of airways becomes inflammed and produces excess of mucous.
Asthma is generally triggered by dust particles or allergens which is found in the air. It is a very common problem and if affects many people around the world.
The people suffering from asthma must avoid dusty and smoky places to avoid or reduce asthmatic attacks.
