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

Fact 2: Mammals breathe air with lungs.

Given the two facts above, answer the question "What may be caused by an infection or injury of the organs used to breathe air?" with the following options: 
- Toxicity
 - smoking
 - fertilization
 - pneumonia
 - a broken leg
 - oxygenation
 - Dehydration
 - the skin


 

    pneumonia     