Which one of the following is $NOT$ a psychological disorder?

$CO$ (Carbon monoxide) is harmful because:

When $O_2$ is inadequate during respiration,the condition is called:

The disease called pleurisy is due to:

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.

Air pollution can result in emphysema,which is: