In pneumonia, where does the fluid accumulate?

Assertion $A$: Pneumonia is a serious respiratory disease.
Reason $R$: The accumulation of fluid in the alveoli and bronchioles prevents sufficient oxygen from reaching the lungs.
Which option is correct for Assertion $A$ and Reason $R$?

Which one of the following is the correct statement for respiration in humans?

Anoxia is a condition when:

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

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