Fact 1: Pneumonia may be caused by an infection or injury of the lungs.

Fact 2: Smoke inhalation and thermal lung injury cause direct lung injury.

Given the two facts above, answer the question "Pneumonia may be caused by an infection or what?" with the following options: 
- smoke inhalation
 - Veins and arteries.
 - deadly and devastating
 - breathing deeply
 - clean air
 - expanding organs
 - the body's largest organ
 - Damages them


 

 smoke inhalation        