Fact 1: Amold spore has a negative impact on the respiratory system.

Fact 2: Major components of the respiratory system are the lungs, trachea, nose, and the cell.

Given the two facts above, answer the question "What has a negative impact on the lungs?" with the following options: 
- unpolluted air
 - healthy atmosphere
 - mold spore
 - smoking
 - disease
 - influenza
 - clean air
 - A virus


 

   mold spore      