One of the major causes of emphysema is

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 $R$?

The turning of fingernails to a greyish-blue color is a symptom of which disease?

Tobacco smoke contains carbon monoxide which

Which of the following is a symptom of pneumonia?

The state during which the respiratory centre is inhibited is termed as: