Mountain sickness is caused by:

Cyanosis refers to:

Which of the following is an occupational respiratory disease?

$A$ - Smoking is associated with increased incidence of cancer of lung.
$R$ - It increases $CO$ content in blood and reduces the concentration of haem-bound oxygen.

Assertion $(A):$ $A$ person goes to high altitude and experiences 'altitude sickness' with symptoms like breathing difficulty and heart palpitations.
Reason $(R):$ Due to low atmospheric pressure at high altitude,the body does not get sufficient oxygen.
In the light of the above statements,choose the correct answer from the options given below.

Which of the following is a chronic respiratory disorder?