In pneumonia, where does the fluid accumulate?

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.

Tobacco smoke contains carbon monoxide which

Complete bronchus obstruction results in

In severe cases of which of the following diseases may the lips and fingernails turn gray to bluish in color?

Which of the following is a bacterial disease of the respiratory system?