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

Fact 2: Viral pneumonia is usually milder than bacterial pneumonia.

Given the two facts above, answer the question "Viral and what disease can both be caused by injury of the lungs" with the following options: 
- tongue
 - the skin
 - bacterial
 - throat
 - Pollution
 - fungi
 - smoking
 - ribs


 

   bacterial      